MEMORANDUM OPINION AND ORDER

COLLEEN KOLLAR-KOTELLY, District Judge.

Plaintiff Pearl Gaither ("Plaintiff"), the representative of the estate of Mikal R. Gaither ("Gaither"), brings this action against the District of Columbia (the "District") and a series of individual defendants seeking damages in connection with Gaither's fatal stabbing while he was incarcerated pending sentencing at the District's Central Detention Facility. Plaintiff has indicated an intention to present expert testimony at trial from Michele Roberts, Esq. ("Roberts") concerning the sentence Gaither likely would have received had he survived in support of her alleged damages. The matter comes to this Court on the District's [113] Motion to Strike Plaintiff's Expert Michelle [sic] Roberts, Esq. ("Motion to Strike"); the Honorable Magistrate Judge Alan Kay's [120] Memorandum Order resolving the District's Motion to Strike; Plaintiff's [235] Updated Memorandum in Support of Expert Testimony of Plaintiff's Sentencing Expert; the District's [246] Updated Memorandum in Opposition to Plaintiff's Updated Memorandum in Support of Plaintiff's Sentencing Expert; and Plaintiff's [236] Motion for Leave to Supplement Expert Report of Michele Roberts, Esq. ("Motion to Supplement"). Upon consideration of the parties' submissions, the relevant authorities, and the record as a whole, the Court concurs with Magistrate Judge Kay that Roberts should be precluded from testifying as to her opinion of the sentence that Gaither likely would have received in his criminal case. However, the Court finds that Roberts may provide generalized testimony about the factors that a judge might take into account in the course of sentencing a criminal defendant, an issue that was not addressed by Magistrate Judge Kay in his Memorandum Order.

I. BACKGROUND

The Court assumes familiarity with its prior opinions in this action, which set forth in detail the extensive factual and procedural background of this case.

On December 14, 2002, Gaither was fatally stabbed by a fellow inmate while incarcerated at the District's Central Detention Facility. A subsequent investigation concluded that two of Gaither's fellow inmates had forced Gaither into an open cell and proceeded to stab him, and indications were that Gaither had been killed because of his involvement in a grand jury investigation into the murder of an individual by the name of Kenneth Muldrow.

Plaintiff brings this action on behalf of Gaither's estate. She asserts claims under, inter alia, Section 1 of the Ku Klux Act of 1871, Rev. Stat. § 1979, as amended, 42 U.S.C. § 1983, against the District and a series of individual officials and correctional officers, seeking compensatory damages against each defendant in the amount of $10 million.

Significantly, at the time of his death, Gaither had already pleaded guilty to one felony count of distribution of cocaine and was awaiting sentencing in the Superior Court of the District of Columbia by the Honorable Judge Noël Anketell Kramer, who was then the Presiding Judge of the Criminal Division.1 Under the statute that applied at the time, Gaither's conviction carried a possible sentence ranging from probation to thirty years' incarceration. See D.C. CODE § 33-541(a)(1) (1981). Due to Gaither's untimely death, his actual sentence will never be known. Nevertheless, because the parties agree that Gaither would not have suffered lost wages for any period that he was incarcerated, the sentence Gaither likely would have received is an important ingredient of Gaither's lifetime earning potential, which in turn is a large part of Plaintiff's claimed compensatory damages in this case. Distilling the matter to its essence, should the jury ever need to reach the issue, the less time it finds that Gaither would have spent in jail, the greater Plaintiff's damages.

For this reason, during the course of discovery, Plaintiff designated Roberts to testify as a "sentencing expert" and, more precisely, to provide an opinion as to the sentence that Gaither likely would have received had he lived.2 Roberts subsequently prepared, and Plaintiff produced, a three-page written report, in which she stated her "opinion that, had he lived, Mr. Gaither would have been sentenced to probation for his first felony conviction on a single count of distribution of cocaine." Report of Michele A. Roberts, Esq. ("Roberts' Rep."), ECF No. [113-3], at 1. According to her report, Roberts based her opinion on the following:

See id. at 1.

While acknowledging that "the statutory maximum sentence for distribution of cocaine was 10 to 30 years at the time of Mr. Gaither's offense," Roberts opines in her report that "a defendant without a prior felony conviction was more likely than not to receive a sentence of probation upon conviction for this offense, both according to the relevant historical data and based on [her] own experience." Id. According to Roberts, "[t]hat is because judges were generally concerned about proportionality in sentencing — i.e., treating like offenders alike — and, consequently, exercised their sentencing discretion in a manner that took into account criminal history as well as mitigating factors." Id. In her report, Roberts identifies three "aggravating factors" and nine "mitigating factors"3 that she contends supports her opinion that Gaither likely would have received probation as a sentence. Id. at 2-3. The three aggravating factors include:

See id. at 2. Meanwhile, the nine mitigating factors identified by Roberts in her report are as follows:

Id. at 2-3.

Believing that Roberts' opinion, as set forth in her written report, did not satisfy the requirements of Rule 702 of the Federal Rules of Evidence, the District filed its [113] Motion to Strike, seeking to preclude Roberts from testifying on how a presiding judge may have ruled in Gaither's case. See Mem. of P. & A. in Supp. of Defs.' Mot. to Strike Pl.'s Expert Michelle [sic] Roberts, ECF No. [113]. Plaintiff subsequently filed an opposition, the District filed a reply, and, with the Court's leave, Plaintiff filed a surreply. See Pl.'s Opp'n to the District of Columbia's Mot. to Strike Pl.'s Sentencing Expert Roberts, ECF No. [114]; Def. District of Columbia's Reply to Pl.'s Opp'n to the District of Columbia's Mot. to Strike Expert Michelle [sic] Roberts, ECF No. [115]; Pl.'s Sur-Reply in Opp'n to the District of Columbia's Mot. to Strike Pl.'s Experts, ECF No. [119]. In a detailed [120] Memorandum Order, Magistrate Judge Kay, to whom this action was referred under Local Civil Rule 72.2(a), granted the District's Motion to Strike in relevant part. Magistrate Judge Kay concluded that Roberts should be precluded from testifying as to the opinion that Gaither likely would have received probation had he lived, finding that the methodology underlying her opinion, as reflected in her three-page written report, failed to meet the standards of reliability set forth in Rule 702. Magistrate Judge Kay was neither asked to, nor did, determine whether Roberts could provide more generalized testimony, such as testimony about the factors judges are likely to consider when sentencing a criminal defendant.

Subsequently, Plaintiff filed objections to Magistrate Judge Kay's ruling, and the District filed a response to those objections. See Pl.'s Mem. of Law in Supp. of Her Objections to Magistrate Judge Kay's Order Granting in Part the District's Mot. to Strike Pl.'s Experts, ECF No. [126-1]; Def. District of Columbia's Mem. of P. & A. in Opp'n to Pl.'s Mem. of Law in Supp. of Her Objections to Judge Kay's Order Granting the District's Mot. to Strike Pl.'s Sentencing Expert, ECF No. [129]. The Court heard oral argument on Plaintiff's objections, during which the Court raised various questions concerning Roberts' methodology and her ultimate conclusion. See Tr. of Status Hr'g, ECF No. [187]. Later, without objection, the Court held a thorough Daubert hearing,4 during which the parties had a full and fair opportunity to probe the reliability of Roberts' methodology and conclusions. See Tr. of Daubert Hr'g, ECF No. [188]. Following the hearing, the parties filed supplemental memoranda addressing the reliability of Roberts' proffered testimony. See Def. District of Columbia's Suppl. Mem. of P. & A. in Opp'n to Pl.'s Objections to Judge Kay's Order Granting the District's Mot. to Strike Michele Roberts, Esq., as a Sentencing Expert in this Case, ECF No. [153]; Pl.'s Am. Opp'n to Defs.' Suppl. Mem. of P. & A. in Opp'n to Pl.'s Objections to Magistrate's Order Striking Pl.'s Sentencing Report, ECF No. [172-1]; Pl.'s Am. Notice of Filing of Signed Decl. of Michele A. Roberts, Esq., ECF No. [177]; Defs.' Reply to Pl.'s Opp'n to Defs.' Suppl. Mem. of P. & A. in Opp'n to Pl.'s Mem. of Law in Supp. of Her Objections to Judge Kay's Order Granting in Part the District's Motion to Strike Pl.'s Experts, ECF No. [176].

Thereafter, a number of developments changed the landscape of this case. Most notably, the Court resolved the parties' cross-motions for summary judgment and granted Plaintiff leave to amend her complaint. See Estate of Gaither ex rel. Gaither v. District of Columbia, 655 F.Supp.2d 69 (D.D.C.2009). Accordingly, the Court invited the parties to inform the Court whether they believed additional briefing as to the admissibility of Roberts' testimony would be desirable. See Order, ECF No. [222]. After the parties weighed in, the Court set a schedule for the submission of updated memoranda. See Min. Order (Mar. 31, 2011). The parties were directed to file consolidated memoranda and were expressly warned that their "submissions must raise any and all arguments they may have regarding the admissibility of Roberts' testimony at trial" and that the Court would "not consider prior submissions." Id. (emphasis added). Plaintiff filed her memorandum on April 20, 2011. See Pl.'s Updated Mem. in Supp. of Expert Test. of Pl.'s Sentencing Expert ("Pl.'s [235] Mem."), ECF No. [235]. The District filed its memorandum on May 11, 2011. See Def.'s Updated Mem. in Opp'n to Pl.'s Updated Mem. in Supp. of Pl.'s Sentencing Expert ("Def.'s [246] Mem."), ECF No. [246]. These memoranda supersede the parties' prior submissions on this matter and, as a result, are the primary focus of the Court's attention in this Memorandum Opinion and Order.

Plaintiff claims to have discovered additional materials supporting Roberts' opinion since the Court held the Daubert hearing. Specifically, Plaintiff has since located:

Plaintiff filed her [236] Motion to Supplement, seeking leave to supplement Roberts' expert report to reference these additional materials. See Pl.'s Mem. of P. & A. in Supp. of Her Mot. for Leave to Supplement Expert Report of Michele Roberts, Esq., ECF No. [236-1]. The District filed an opposition to Plaintiff's Motion to Supplement. See Def.'s Mem. of P. & A. in Opp'n to Pl.'s Mot. to Supplement Expert Report of Michele Roberts, Esq., ECF No. [245]. Plaintiff filed a reply. See Reply in Supp. of Pl.'s Mot. for Leave to Supplement Expert Report of Michele Roberts, Esq., ECF No. [251]. In her proposed supplemental written report, Roberts references the additional materials to support "additional mitigating facts." Suppl. Report of Michele A. Roberts, Esq. ("Suppl. Roberts' Rep."), ECF No. [236-10], at 3. Her underlying opinion, and accompanying methodology, remain fundamentally the same as in her original written report. See id. at 1.

II. LEGAL STANDARD

Rule 702 of the Federal Rules of Evidence governs the admission of expert testimony:

FED.R.EVID. 702.5 The trial judge has "considerable leeway in deciding in a particular case how to go about determining whether particular testimony is reliable." Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137, 152, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999). "Exactly how reliability is evaluated may vary from case to case, but what remains constant is the requirement that the trial judge evaluate the reliability of the testimony before allowing its admission at trial." United States v. Frazier, 387 F.3d 1244, 1262 (11th Cir.2004) (en banc), cert. denied, 544 U.S. 1063, 125 S.Ct. 2516, 161 L.Ed.2d 1114 (2005). In all cases, "[t]he trial judge ... must find that [the proffered testimony] is properly grounded, well-reasoned and not speculative before it can be admitted." FED. R.EVID. 702 advisory committee's note (2000 amends.).

III. PRELIMINARY MATTERS

As a preliminary matter, the parties disagree as to the scope of the Court's review of the District's [113] Motion to Strike, which comes to this Court upon Plaintiff's objections to Magistrate Judge Kay's [120] Memorandum Order granting the District's motion in relevant part and precluding Roberts from testifying at trial as to the sentence Gaither likely would have received had he survived. Because the motion was decided by Magistrate Judge Kay pursuant to a reference under Local Civil 72.2(a), this Court may modify or set aside any portion of his decision "found to be clearly erroneous or contrary to law." LCVR 72.2(c); accord 28 U.S.C. § 636(b)(1)(A); FED.R.CIV.P. 72(a). In the abstract, this means that the Court conducts a plenary review of matters of law, but is bound by Magistrate Judge Kay's findings of fact and discretionary determinations unless they are clearly erroneous. Am. Ctr. for Civil Justice v. Ambush, 794 F.Supp.2d 123, 129-30 (D.D.C. 2011). However, because the admissibility of expert testimony frequently turns on legal questions "intertwined with factual issues that are in turn tinged with aspects of discretion," Charles A. Wright et al., FEDERAL PRACTICE AND PROCEDURE § 3069 (2d ed. 1987), the scope of the Court's review is "not monolithic," Milward v. Acuity Specialty Prods. Grp., Inc., 639 F.3d 11, 13 (1st Cir.2011) (citation omitted); see also Norris v. Baxter Healthcare Corp., 397 F.3d 878, 883 (10th Cir.2005). Nonetheless, the guiding principle — that the trial judge may not substitute her judgment for the magistrate's — remains the same.

However interesting the interaction between these principles may be, they need not detain the Court long here for the simple reason that the result is the same regardless of the standard of review applied. On the one hand, the Court finds that Magistrate Judge Kay's determination that Roberts should be precluded from testifying about the sentence that Gaither likely would have received had he survived is not clearly erroneous, contrary to law, or an abuse of discretion. On the other hand, even if the Court were to subject the admissibility of Roberts' testimony to plenary review, it would similarly conclude, in an exercise of its broad discretion, that Roberts should be precluded from testifying about the sentence that Gaither likely would have received had he lived to be sentenced in his criminal case.

For purposes of economy and clarity, the Court's discussion below shall be styled simply as if the Court conducted a plenary review, the standard of review that is more generous to Plaintiff's position. Such an approach is particularly useful in this case because, in the time since Magistrate Judge Kay rendered his opinion, the parties have refined their positions and legal arguments and the Court has the benefit of having conducted a Daubert hearing. It is also helpful because some of the matters now before the Court were not before Magistrate Judge Kay at all, including Plaintiff's [236] Motion to Supplement and the question of whether Roberts may provide generalized testimony about the factors that a judge might take into account in the course of sentencing a criminal defendant. See Liberty Lobby, Inc. v. Rees, 852 F.2d 595, 599 (D.C.Cir.1988) (noting that matters that were not before the magistrate judge are not binding on the district court), cert. denied, 489 U.S. 1010, 109 S.Ct. 1118, 103 L.Ed.2d 181 (1989).

IV. DISCUSSION

Plaintiff has indicated her intention to call Roberts at trial to testify as to her "opinion that, had he lived, Mr. Gaither would have been sentenced to probation for his first felony conviction on a single count of distribution of cocaine." Roberts' Rep. at 1; see also Suppl. Roberts' Rep. at 1 (same). More precisely, in a refinement that did not crystallize until after Magistrate Judge Kay rendered his decision, Plaintiff intends to call Roberts to testify "about how a reasonable judge (including Judge Kramer) would have decided Mr. Gaither's sentence and that the likely sentence would have been probation."6 Pl.'s [235] Mem. at 1. The District challenges the admissibility of Roberts' proffered testimony under Rule 702 of Federal Rules of Evidence, which requires Roberts' opinion to be (1) "help[ful to] the trier of fact," (2) "based on sufficient facts or data," and (3) "the product of reliable principles and methods," that are (4) "reliably applied ... to the facts of the case." FED.R.EVID. 702.7 For the reasons set forth below, the Court concurs with Magistrate Judge Kay that Roberts should be precluded from testifying as to her opinion of the sentence that Gaither likely would have received in his criminal case, regardless of whether that testimony is framed in terms of how a "reasonable judge" or how Judge Kramer would have sentenced Gaither. However, the Court finds that Roberts may provide generalized testimony about the factors that a judge might take into account in the course of sentencing a criminal defendant.

A. Plaintiff Has Conceded that Roberts Cannot Testify as to the Sentence Judge Kramer Likely Would Have Imposed in Gaither's Criminal Case

The Court begins by denoting what is no longer in dispute. According to Plaintiff, Roberts will "testify about how a reasonable judge ... would have decided Mr. Gaither's sentence." Pl.'s [235] Mem. at 1 (emphasis added). She disclaims that Roberts will "make any attempt to predict the likely sentence Judge Kramer would have imposed." Id. at 19 (emphasis added). Based on this explicit concession, the Court shall preclude Roberts from testifying as to the sentence Judge Kramer likely would have imposed in Gaither's criminal case.

B. Roberts Cannot Testify as to Her Opinion that Judge Kramer Was "Down the Middle" and "Not an Outlier" in Her Sentencing Practices

In a stunning feat of legal jujitsu, Plaintiff at one moment disclaims that Roberts will "make any attempt to predict the likely sentence Judge Kramer would have imposed," Pl.'s [235] Mem. at 19, and then proceeds to represent that Roberts will testify "about how a reasonable judge (including Judge Kramer) would have decided Mr. Gaither's sentence," id. at 1 (emphasis added). Through this act of contortion, Plaintiff, quite transparently, seeks to backdoor an opinion about the sentence Judge Kramer likely would have imposed in Gaither's case by characterizing Judge Kramer as a "reasonable judge." But what Plaintiff seems to recognize she cannot get through the front door cannot come in through the back.

Conveniently glossed over by Plaintiff is that she needs Roberts to offer two different opinions to get to her desired end-point. Specifically, Roberts must first opine about how a "reasonable judge" would have sentenced Gaither. Then, she must opine about how Judge Kramer was situated vis-à-vis the so-called "reasonable judge." In this regard, the connective tissue, as it were, is Roberts' opinion that Judge Kramer was "down the middle" and "not an outlier" in her sentencing practices.

Plaintiff's efforts fail at both stages. At the first stage, Roberts cannot offer an opinion as to how a "reasonable judge" would have sentenced Gaither, a matter the Court addresses below. See infra Part IV.C. However, even assuming that Roberts could offer such an opinion, the Court would nonetheless find that Roberts cannot offer an opinion as to whether Judge Kramer was "down the middle" and "not an outlier" in her sentencing practices because Plaintiff has failed to show that such an opinion would be "based on sufficient facts or data" and "the product of reliable principles and methods."8 FED.R.EVID. 702.

At the Daubert hearing, Roberts testified as follows:

Tr. of Daubert Hr'g at 57. But when pressed to explain the basis for her opinion that Judge Kramer is a "reasonable judge," "down the middle," or "not an outlier," Roberts conceded that she had not reviewed data specific to Judge Kramer's historical sentencing patterns, as opposed to judges of the Superior Court as a whole.9 See id. at 62-63, 66-67. Instead, Roberts testified that she has "some sense" of what Judge Kramer's sentencing practices were in the relevant time period because her tenure in the Public Defenders Service "overlapped with the time that Judge Kramer was on the bench." Id. at 17. Despite this assertion, by her own admission, Roberts' opinion of Judge Kramer's sentencing practices "did not come from [her] own experience," id. at 108-09, and she concedes that she has "no memory one way or the other" of whether she ever had a case analogous to Gaither's before Judge Kramer, id. at 70.

With this limited showing, Plaintiff has failed to satisfy the Court that Roberts' opinion about how Judge Kramer was situated vis-à-vis the so-called "reasonable judge" is "based on sufficient facts or data" and "the product of reliable principles and methods." FED. R. EVID. 702. The record is devoid of any meaningful measure of detail about the extent of Roberts' experience with and knowledge of Judge Kramer's sentencing practices specifically. This Court is not required to "admit opinion evidence that is connected to existing data only by the ipse dixit of the expert." Gen. Elec. Co. v. Joiner, 522 U.S. 136, 146, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997). In this case, apart from knowing that Roberts has some knowledge of Judge Kramer's sentencing habits by virtue of her experience (knowledge that is largely secondhand), the Court is left only with Roberts' unvarnished opinion that Judge Kramer is a "reasonable judge," "down the middle," or "not an outlier." Cf. Frazier, 387 F.3d at 1253 (upholding trial judge's decision to exclude expert testimony where expert identified a single specific investigation involving the subject matter of his opinion; the expert "made no effort to quantify in any way the number of cases he was personally involved in" that implicated the same subject matter). To put it simply, there is too great an analytical gap between the factual basis and the proffered opinion to satisfy the Court that Roberts' opinion is "based on sufficient facts or data" and "the product of reliable principles and methods." FED.R.EVID. 702.10 Accordingly, the Court shall preclude Roberts from testifying as to her opinion that Judge Kramer was a "reasonable judge," "down the middle," and "not an outlier" in her sentencing practices.

C. Roberts Cannot Testify as to the Sentence a "Reasonable Judge" Likely Would Have Imposed in Gaither's Criminal Case

The Court now turns to the heart of Roberts' proffered testimony. According to Plaintiff, Roberts will "testify about how a reasonable judge ... would have decided Mr. Gaither's sentence." Pl.'s [235] Mem. at 1. In an exercise of its broad discretion in these matters, the Court finds that Roberts' opinion as to how a "reasonable judge" would have sentenced Gaither should be excluded under both Rule 702 and Rule 403 of the Federal Rules of Evidence. The Court addresses each ground for exclusion in turn.

1. Rule 702

To reiterate, Rule 702 requires Roberts' opinion to be, inter alia, (1) "based on sufficient facts or data," and (2) "the product of reliable principles and methods," that are (3) "reliably applied ... to the facts of the case." FED.R.EVID. 702.

i. "Sufficient Facts or Data"

In this case, the Court shall first assume, without deciding, that Roberts' substantial experience and knowledge of sentencing practices in the Superior Court, the same factors that qualify her as an expert to begin with, coupled with her review of historical sentencing data compiled by others, constitute "sufficient facts or data" to support some form of a predictive judgment about how a judge might sentence a criminal defendant in a particular case. See Tr. of Daubert Hr'g at 19 (identifying the bases for Roberts' proffered opinion); Roberts' Rep. at 1 (same).11 At the very least, the record is consistent with such an assumption. As an experienced practitioner, Roberts was consistently called upon to make a predictive judgment about the sentence a client might receive, and she testified that this task was important to her day-to-day work over the years:

Tr. of Daubert Hr'g at 12-13. To quantify this experience, Roberts claims that she has had some level of involvement in somewhere between 1,500 to 2,400 criminal drug cases in the period from 1988 to 2001, either as a trial attorney or as a supervisor of other trial attorneys. See id. at 96-100; Roberts Decl. ¶ 3. In the time period after Gaither would have been sentenced, Roberts garnered additional experience as a member of the Sentencing Commission for the District of Columbia, which required her involvement in discussions about sentencing philosophies and trends, as well as in her private practice. See Tr. of Daubert Hr'g at 19, 102. On this record, the Court shall assume that Roberts' opinion is "based on sufficient facts or data." FED. R.EVID. 702.12

ii. "Reliable Principles and Methods"

Even with the foregoing assumption, Plaintiff still must show that Roberts' opinion is "the product of reliable principles and methods." FED.R.EVID. 702. In this regard, Plaintiff fairly summarizes Roberts' relied-upon "methodology" for making a predictive sentencing judgment as follows:

Pl.'s [235] Mem. at 10 (citing Tr. of Daubert Hr'g at 36-37, 50-52).13 Plaintiff contends that Roberts' "methodology — comparing the relevant sentencing factors in a particular case to thousands of prior sentences involving similar factors — is sound" because "[m]aking such assessments in advising clients and, later[,] lawyers she supervised, was her stock-in-trade as a highly regarded Assistant Public Defender, in which capacity she generated a considerable volume of sentence comparators." Id. at 1-2.

In tendering this argument, Plaintiff effectively conflates two separate questions under Rule 702 — whether the proffered opinion is "based on sufficient facts or data" and whether it is "the product of reliable principles and methods." FED. R.EVID. 702. The Court does not doubt that there will be some interplay between these questions where, as here, an expert relies primarily on her experience and knowledge as a basis for her opinion. "[N]o one denies that an expert might draw a conclusion from a set of observations based on extensive and specialized experience," Kumho Tire, 526 U.S. at 156, 119 S.Ct. 1167, and in some cases, "the relevant reliability concerns may focus on personal knowledge or experience," id. at 150, 119 S.Ct. 1167. But that "does not mean that experience, standing alone, is a sufficient foundation rendering reliable any conceivable opinion the expert may express." Frazier, 387 F.3d at 1261. Even when an expert relies upon her experience, "the reliability criterion remains a discrete, independent, and important requirement for admissibility." Id. Thus, where, as here, the expert relies "primarily on experience, then the witness must explain how that experience leads to the conclusion reached, why that experience is a sufficient basis for the opinion, and how that experience is reliably applied to the facts." FED.R.EVID. 702 advisory committee's note (2000 amends.); accord Metavante Corp. v. Emigrant Sav. Bank, 619 F.3d 748, 761 (7th Cir.2010), cert. denied, ___ U.S. ___, 131 S.Ct. 1784, 179 L.Ed.2d 653 (2011).

Because the standards for the admission of expert testimony are flexible by design, the trial judge's discretion extends not only to her substantive judgment, but also to her threshold determination as to how reliability should be evaluated. Kumho Tire, 526 U.S. at 152, 119 S.Ct. 1167. In this regard, the Court is in complete agreement with Plaintiff that the law does not support the rigid application of the factors articulated by the United States Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993).14 The Court also agrees with Plaintiff that Roberts' testimony is not per se inadmissible simply because, as Plaintiff concedes, it is "unsupported by peer review" and "lack[s] statistical analysis or studies," Pl.'s [235] Mem. at 13, factors that are commonly associated with scientific or technical expert testimony. The Court also accepts that the sort of testimony at issue in this case does not easily lend itself to scholarly review or traditional scientific evaluation. Nonetheless, the Court departs with Plaintiff to the extent she intends to suggest that the factors identified in Daubert are irrelevant in this case. Daubert should not be "slavishly applied" in this context. Id. at 17. But neither should it be disregarded.

Contrary to what Plaintiff may believe, "some of Daubert's questions can help to evaluate the reliability even of experience-based testimony." Kumho Tire, 526 U.S. at 151, 119 S.Ct. 1167. In particular, the Supreme Court has acknowledged that, in some cases, it will be appropriate to ask how often an expert's experience "has produced erroneous results."15 Id. This happens to be one of those cases. In this case, even while acknowledging that Gaither's conviction carried a possible sentence ranging from probation to thirty years' incarceration, Roberts' opinion is that, "had he lived, Mr. Gaither would have been sentenced to probation." Roberts' Rep. at 1. This is a predictive judgment, and a rather precise one at that.

Given the nature of the proffered opinion, the Court would expect Plaintiff to offer some indication of the "rate of error" of Roberts' predictive methodology. Daubert, 509 U.S. at 594, 113 S.Ct. 2786. To put it in the most simple terms, while the Court has no doubt that Roberts was consistently called upon to make predictive judgments about the sentence clients might receive in the course of her extensive and impressive career, there is no evidence in the record indicating how good she was at making such judgments. Roughly speaking, how often did Roberts' predictions turn out to be correct? When incorrect, how often were they "in the ballpark" and how often did they deviate significantly from the sentence actually imposed? These questions, which are left unanswered in the record before the Court, are the sort of questions one would expect to be addressed where a party intends to call a witness to make a predictive judgment like the one at issue here, even when that judgment is primarily based on the expert's experience and not a more rigorous scientific or technical inquiry.16 By this, the Court does not intend to suggest that Plaintiff was somehow obligated to establish the reliability of Roberts' methodology to a scientific or statistical certainty; even generalized evidence about how often Roberts' methodology produces erroneous results might very well have sufficed in this case. However, the record created by the parties in this case is devoid of any such evidence. At best, the record suggests that Roberts' powers of prediction improved as her career progressed. See Tr. of Daubert Hr'g at 36-37, 55. This evidence does not provide the Court with any metric, even a rough and non-scientific metric, to probe the reliability of Roberts' predictive methodology. In the end, Roberts' "bald assurance of validity is not enough" for this Court. Daubert v. Merrell Dow Pharm., Inc., 43 F.3d 1311, 1316 (9th Cir.), cert. denied, 516 U.S. 869, 116 S.Ct. 189, 133 L.Ed.2d 126 (1995).17 On this record, Plaintiff has failed to satisfy the Court that Roberts' opinion that a reasonable judge would likely have sentenced Gaither to probation is "the product of reliable principles and methods." FED. R.EVID. 702.

iii. "Reliably Applied"

Nor is the Court satisfied that Roberts' methodology has been "reliably applied... to the facts of the case," FED. R.EVID. 702, to yield her opinion that a "reasonable judge" likely would have sentenced Gaither to probation. As an initial matter, the Court harbors no small amount of doubt that such a methodology could ever reliably produce such a precise prediction. Roberts' predictive methodology is meant to duplicate the "methodology" used by sentencing judges. But that methodology, to the extent it may even be characterized as such, is fact-intensive, multifaceted, open-ended, and discretionary. Indeed, the courts of the District of Columbia recognize that two jurists, even when presented with the same set of facts, may reach different outcomes when "the discretionary, virtually non-reviewable act[,] of sentencing takes place." Belton v. United States, 581 A.2d 1205, 1212 (D.C. 1990). What is an appropriate sentence in a particular case? In the District of Columbia, as elsewhere, "reasonable men may and do differ on the subject." Foster v. United States, 290 A.2d 176, 179 (D.C. 1972).18 To put it another way, reasonable minds could apply the same "methodology" as Roberts and end up with two different and equally valid outcomes. See also Tr. of Daubert Hr'g at 75-76, 84 (conceding that judges could exercise their discretion differently).

More to the point, Roberts' testimony at the Daubert hearing about how she applied her methodology to Gaither's case was replete with generalities. She repeatedly opined that certain facts pertinent to Gaither's criminal case would be "critical," "significant," or a "huge plus" in sentencing, while others would merit "some consideration" or would not be "dealbreakers." Framed in such generalized and non-specific terms, the Court has no basis to meaningfully assess whether Roberts has reliably applied her methodology to predict that a "reasonable judge" would have sentenced Gaither to probation. In the final analysis, it is not really clear what weight Roberts herself applied to each factor, let alone why a "reasonable judge" would do the same.

Plaintiff's reliance on a series of cases, none of them binding on this Court, addressing the propriety of expert testimony on the "reasonable judge" in legal malpractice actions, is misplaced. See Pl.'s [235] Mem. at 20. As the District observes, in legal malpractice actions, the jurors' job is to put themselves in the place of the trier of fact in the prior legal action and to determine "what the result should have been" — that is, to hold a "trial within a trial." In re DeAtley Litig., No. CV-06-0278-JLQ, 2008 WL 375086, at *6 (E.D.Wash. Feb. 11, 2008). The goal is not to predict what a particular trier of fact would have done as a matter of historical fact or hypothesis. That fiction, which allows the jury to substitute its judgment for another trier of fact, does not apply in this context. Here, "the question is not what Mr. Gaither should have earned, but rather what he would have earned, a determination that depends in part on what sentence he would have received, not what sentence the jury believes he should have received." Def.'s [246] Mem. at 18.

Plaintiff also relies upon a series of cases in which a judge expressed some level of willingness to hear expert sentencing testimony before sentencing a criminal defendant or making a determination concerning release on bail. See Pl.'s [235] Mem. at 16-17. These cases, none of which are binding on this Court, are inapposite for myriad reasons, but only one need be mentioned here: the Federal Rules of Evidence, and by extension the entire inquiry at issue here, do not apply in such proceedings. See FED.R.EVID. 1101(d)(3). In the end, the authorities cited by Plaintiff simply are not apposite.

The Court's conclusion remains the same even after taking into account the historical sentencing data that Roberts reviewed in rendering her opinion. See Pl.'s [235] Mem. at 1 (claiming that "the historical sentencing data ... shows that Ms. Roberts' applied her method reliably because this data strongly supports a conclusion that probation (or a similarly short sentence) was likely."). Strictly speaking, this evidence does not directly verify the reliability of Roberts' predictive methodology, which is based on her application of a multi-factored, discretionary balancing test to the facts of a particular case. Rather, as Roberts and Plaintiff suggest, the evidence at best "corroborates" or "boosts" her bottom-line opinion that Gaither likely would have been sentenced to probation had he survived. Id. at 11; see also Tr. of Daubert Hr'g at 21 (stating that the historical data "confirmed the opinion that [Roberts] initially arrived at"). The historical data indicates that, between January 1, 1996 and June 30, 2003, 52% of individuals charged with the same offense as Gaither and falling in the same criminal history category received probation. See App'x: Historical Data for Drug Grid ("Historical Data App'x"), ECF No. [235-11], at 1. Meanwhile, 48% of those individuals were sentenced to some period of incarceration.19 Id. But Plaintiff does not claim that Roberts (or, for that matter, anyone else) ever looked behind the data to determine the composition of these groups — that is, to determine how the factual circumstances of the criminal defendants behind the raw data coincide with the actual sentences imposed. Without that connection, there is an unacceptable analytical disconnect between Roberts' opinion, her predictive methodology, and the historical data. Stated differently, there is nothing in the data, or Roberts' analysis of the data, that reveals that she reliably concluded that Gaither would have fallen into the 52% of the group that received probation instead of the 48% who did not.

For this reason, and for the reasons set forth above, the Court is not satisfied that Roberts' methodology has been "reliably applied ... to the facts of the case," FED. R.EVID. 702, to yield her opinion that a "reasonable judge" likely would have sentenced Gaither to probation in his criminal case.

2. Rule 403

As observed by the Supreme Court, an expert's opinion "can be both powerful and quite misleading because of the difficulty in evaluating it." Daubert, 509 U.S. at 595, 113 S.Ct. 2786. Accordingly, "sometimes expert opinions that otherwise meet the admissibility requirements [of Rule 702] may still be excluded by applying Rule 403." Frazier, 387 F.3d at 1263. Indeed, "Rule 403 exclusion based on unfair prejudice is particularly important in the case of expert evidence." U.S. ex rel. Miller v. Bill Harbert Int'l Constr., Inc., 608 F.3d 871, 895 (D.C.Cir. 2010), cert. denied, ___ U.S. ___, 131 S.Ct. 2443, 179 L.Ed.2d 1208 (2011). In this case, even assuming, arguendo, that Roberts' proffered testimony would meet the requirements of Rule 702, the court would exercise its discretion and conclude that whatever probative value such testimony would have would be "substantially outweighed" by "a danger of unfair prejudice... [and] misleading the jury." FED. R.EVID. 403. At the very best, the methodological foundation for Roberts' proffered opinion that Gaither would be sentenced to probation is "slender," and the danger that the jury would assign such testimony talismanic significance is too great. Frazier, 387 F.3d at 1263.

In sum, the Court finds that Plaintiff has failed to show that Roberts' opinion that a "reasonable judge" would have sentenced Gaither to probation is "the product of reliable principles and methods" that are "reliably applied ... to the facts of the case." FED.R.EVID. 702. Alternatively, the Court finds that whatever probative value such testimony would have would be "substantially outweighed" by "a danger of unfair prejudice ... [and] misleading the jury." FED.R.EVID. 403. Accordingly, the Court shall preclude Roberts from testifying as to how a "reasonable judge" would have sentenced Gaither.20

D. Roberts Can Provide Generalized Testimony About the Factors that a Judge Might Take into Account When Sentencing a Criminal Defendant

Despite the foregoing, the Court agrees that the jury will need some guidance in determining what sentence Gaither likely would have received in order to calculate Plaintiff's claimed compensatory damages, should they ever need to reach that question. Laypersons are unlikely to know the factors that judges are likely to consider in sentencing and, absent such testimony, the jury in this case would have little at its disposal to evaluate what sentence within the wide range of possible sentences Gaither might have received. The Court declines to cast the jury adrift in a sea of speculation.

In this regard, the Court finds that Roberts can testify, in general terms, as to the factors that a judge might take into account in the course of sentencing a criminal defendant (e.g., the nature of the offense, prior criminal history, whether the offender pleads guilty or is convicted at trial, social and family history, employment history, ties to the community, etc.). See FED.R.EVID. 702 advisory committee's note (2000 amends.) (recognizing that it might "be important in some cases for an expert to educate the factfinder about general principles, without ever attempting to apply these principles to the specific facts of the case.").21 In addition, Roberts may respond to appropriate hypothetical questions designed to elicit an opinion as to whether certain factors would be a positive or negative consideration in sentencing. See Estate of Carey by Carey v. Hy-Temp Mfg., Inc., 929 F.2d 1229, 1235 n. 2 (7th Cir.1991) ("[E]xpert witnesses may be competent to give opinions based on hypothetical facts even though a foundation that the expert has personal knowledge of those facts has not been laid.") (citation omitted). For example, Plaintiff's counsel may ask Roberts whether a criminal defendant's voluntary cooperation in a grand jury investigation is likely to be viewed as a positive factor in determining the defendant's ultimate sentence. However, the use of such hypothetical questions shall be conditioned upon Plaintiff's ability to lay a proper foundation connecting the hypothetical scenarios to the actual facts of this case through other evidence or witnesses.

Meanwhile, the Court emphasizes that Roberts' testimony cannot stray into the following areas: (1) her opinion of the sentence that Judge Kramer or a "reasonable judge" would have imposed in Gaither's criminal case; (2) her opinion of how Judge Kramer was situated vis-à-vis the "reasonable judge"; (3) her opinion of how a judge would allocate the weight between certain factors (e.g., an opinion that a judge would consider a criminal defendant's successful participation in a drug rehabilitation program as more significant than subsequently testing positive for drug use in violation of the defendant's terms of release); and (4) her interpretation of Judge Kramer's, counsel's, or the probation officer's conduct or statements in Gaither's criminal case (e.g., the reasons why Judge Kramer may have attended Gaither's graduation from a drug rehabilitation program).

With those provisos, in an exercise of its broad discretion, the Court shall permit Roberts to testify, in general terms, as to the factors that a judge might take into account in the course of sentencing a criminal defendant and to respond to appropriate hypothetical questions designed to elicit an opinion as to whether certain factors would be a positive or negative consideration in sentencing, leaving to the jury the task of determining which factors best fit the facts of this case. See Miller, 608 F.3d at 895 (upholding the trial judge's allowance of expert testimony describing generic economic principles, leaving the trier of fact to determine which scenario best fit the facts of the case).

E. Plaintiff's Motion to Supplement Shall Be Denied

In her [236] Motion to Supplement, Plaintiff seeks leave to supplement Roberts' written report to make reference to additional materials supporting Roberts' proffered opinion that a reasonable judge likely would have sentenced Gaither to probation — materials that Plaintiff claims to have discovered since the Court held the Daubert hearing, including a Presentence Investigation Report and transcripts of hearings before Judge Kramer. In her proposed supplemental written report, Roberts references the additional materials as supporting "additional mitigating facts." Suppl. Roberts' Rep. at 3. Her underlying opinion, and accompanying methodology, remain fundamentally the same as in her original written report. See id. at 1. The Court has carefully considered these additional materials, and the corresponding changes made in Roberts' proffered supplemental report, and finds that they would not alter the Court's decision even if supplementation were permitted. Most notably, like the historical sentencing data Roberts relied upon previously, these additional materials at best corroborate or bolster Roberts' underlying conclusion; they do not satisfy the Court that her opinion that a "reasonable judge" would have sentenced Gaither to probation is "the product of reliable principles and methods" that are "reliably applied ... to the facts of the case." FED.R.EVID. 702. At the same time, the additional materials are specific to the facts of Gaither's case, and are therefore irrelevant to the generalized testimony about sentencing factors that the Court has allowed. Accordingly, Plaintiff's [236] Motion to Supplement shall be DENIED because consideration of the proposed supplemental report would not alter the Court's conclusion about the proper scope of Roberts' testimony at trial.22

V. CONCLUSION AND ORDER

The Court has considered the remaining arguments tendered by the parties and has concluded that they are either without merit or need not be addressed in light of the basis for the Court's decision. Therefore, and for the reasons set forth above, it is, this 19th day of December, 2011, hereby

ORDERED that Roberts is PRECLUDED from testifying as to (1) her opinion of the sentence Judge Kramer likely would have imposed in Gaither's criminal case, (2) her opinion that Judge Kramer was a "reasonable judge," "down the middle," and "not an outlier" in sentencing, and (3) her opinion as to how a "reasonable judge" would have sentenced Gaither. However, Roberts may testify, in general terms, as to the factors that a judge might take into account in the course of sentencing a criminal defendant and respond to appropriate hypothetical questions designed to elicit an opinion as to whether certain factors would be a positive or negative consideration in sentencing. Accordingly, Magistrate Judge Kay's [120] Memorandum Order is AFFIRMED in relevant part.

It is FURTHER ORDERED that Plaintiff's [236] Motion to Supplement is DENIED.

SO ORDERED.