GLENN T. HARRELL, JR., J. (Retired, Specially Assigned)

Perhaps the Beatles were expressing skepticism about self-styled experts and their opinions or just singing nonsense lyrics. Courts do not have the luxury to be ambiguous about such things. They are called upon frequently to assess the qualifications of proffered expert witnesses and the worthiness of their proposed opinion testimony as potential aids to fact-finders. This is important especially in complex civil litigation where medical causation is in dispute.1 With roughly equal frequency, Maryland's appellate courts have had recently many opportunities to confront evidentiary questions involving proffered novel science/medical expertise and methodology in Frye/Reed contexts2 or where qualifications or the basis to testify were challenged in non-novel contexts.3

The present case falls in the latter category of challenge. Here, we are confronted with a proffered medical expert who proposed to opine as to the medical causation of deleterious effects from the ingestion of lead-containing paint chips or flakes by a young child and the source of those chips/flakes in or about a specific rental dwelling in downtown Baltimore where the child had resided with his mother. As to medical causation regarding the effects of lead-containing paint ingestion by children generally and the specific child in the present case, the landlord Respondent maintains that the nuances of opining as to medical causation depends critically on such matters as amount and duration of consumption and the development age of the victim at the relevant times, matters of "rigorous" debate within the relevant medical/scientific community and its literature. On these subjects, Respondent sees the Petitioner/victim's expert as ill-suited to offer an opinion that would be of assistance to a fact-finder. Clearly, such matters are not topics of common knowledge of lay people, who would populate most likely the jury in this case. Whether a pediatrician, who has never treated a child victim of lead paint poisoning, but claims to have read the relevant medical literature (or some representative and meaningful portion of it), should be permitted to offer an opinion as to medical causation that would be of some benefit to a lay fact-finder is what we shall decide essentially.4

I.

Jakeem Roy, Petitioner, through his mother, Latisha Hillery, filed suit in negligence in the Circuit Court for Baltimore City against the landlord and owners (collectively "Respondents" or "Dackman") of a dwelling at 2525 Oswego Avenue, Baltimore, for alleged personal injuries resulting from lead-based paint poisoning. The Oswego Avenue property was alleged to be the only source of lead paint ingested by the child. After discovery, Petitioner identified two expert witnesses to testify both as to the source of his lead exposure, but only one of them as to the medical causation of the injuries suffered by Roy. Respondents filed motions to exclude Petitioner's expert witnesses on the basis that, under Maryland Rule 5-702, the experts were not qualified and, if their testimony was excluded, for summary judgment. The Circuit Court granted ultimately summary judgment in favor of Respondent. Without the testimony of Roy's sole medical expert to establish causation, the Circuit Court reasoned that Petitioner could not move to trial on circumstantial evidence alone and, thus, there was no genuine dispute of material fact and Respondent was entitled to judgment as a matter of law. After affirmance of this judgment by the Court of Special Appeals on Petitioner's direct appeal, we granted Roy's petition for a writ of certiorari to consider again what requirements must be met by an expert witness in order to qualify to testify principally as to the medical causation of alleged injuries from childhood lead exposure.

Background

Jakeem Roy, Petitioner (Plaintiff below), was born on 29 April 1996 in Baltimore City. For the first eight months of his life, Roy resided at 2801 Virginia Avenue in the City. Thereafter, Roy, his mother, and his siblings moved to 2525 Oswego Avenue and resided there from approximately the Fall of 1996 through November 1998.5 During this time, 2525 Oswego Avenue, built originally in 1920, was owned and managed by Respondents (Defendants below). Roy, his mother, and his siblings moved from the subject property in November 1998 due to consequential damage from a house fire that occurred in an abutting dwelling.

On 29 June 2011, Roy filed suit in the Circuit Court against Sandra Dackman, individually and as trustee of the assets of Jacob Dackman & Sons, LLC ("the Dackmans"), alleging that the Dackmans provided negligently premises for rent that contained chipping, peeling, and flaking lead paint, in violation of the Baltimore City Housing Code ("Housing Code"), which paint debris was ingested by Roy while living at 2525 Oswego Avenue from 1997-1998. Roy alleged further in his complaint that the Dackmans' awareness of the conditions at 2525 Oswego Avenue was a direct violation of their duty of care to ensure that the property was safe and habitable for tenants. As a result of this alleged exposure at 2525 Oswego Avenue, Roy suffered lead poisoning and permanent injuries. The complaint pleaded multiple counts, including negligence and unfair and deceptive trade practices, in violation of the Maryland Consumer Protection Act, Maryland Code (1975, 2013 Repl. Vol.), Commercial Law § 13-303 ("CL").

In her deposition, Roy's mother, Latisha Hillery, testified that the Oswego Avenue property had flaking and chipping paint throughout the house on the floors, door frames, railings, cabinets, and window sills. On 14 September 2012, at the behest of Petitioner's counsel, the exterior of the property was tested by ARC Environmental, Inc.6, resulting in positive readings for lead on eight of the nine locations tested. No test of the interior surfaces of the dwelling was conducted.7 Between 1997 and 1999, Roy recorded elevated blood-lead levels while living at 2525 Oswego Avenue.8 As noted in the record, Roy's blood-lead levels were measured as follows:

   Sample Date     Blood Lead Level      Plaintiff's Residence

   09/17/1997        15 μg/dL          2525 Oswego Avenue

   11/19/1997        10 μg/dL          2525 Oswego Avenue

   05/15/1998        10 μg/dL          2525 Oswego Avenue

   12/07/1999         9 μg/dL          3710 Haywood Avenue

During discovery, Roy identified Dr. Eric Sundel, a board-certified pediatrician with 20 years in practice, and Robert K. Simon, Ph.D., an industrial hygienist and environmental lead risk assessor, as his anticipated expert witnesses to be called at trial. Dr. Sundel was retained by Petitioner to render opinions about the source of Roy's lead exposure and whether that exposure was the medical cause of Roy's claimed injuries. Dr. Sundel indicated that he would opine, relying on Roy's medical records and other reports, that lead-based paint at 2525 Oswego Avenue caused Roy's medical injuries, including a "loss of IQ points . . ., impaired attention, problems with memory, and problems with coordination."

To support his conclusion, Dr. Sundel relied on the following facts: (1) that the subject property where Roy resided from 8 months to 2 years of age was built in 1920; (2) Roy experienced elevated blood lead-levels while living at the subject property; (3) ARC's testing confirmed the presence of lead-based paint on the exterior of the dwelling; and (4) Roy's mother testified to the existence of chipping, flaking, and peeling paint within the house.9 Dr. Sundel relied also on the in-person neuropsychological evaluation of Roy conducted by neuropsychologist Dr. Barry A. Hurwitz, Ph.D., to find that:

Combining these results with the other facts in the record and a review of relevant literature10, Dr. Sundel concluded "[w]ith a reasonable degree of medical probability, [that he] believe[d] Jakeem Roy suffered injuries from his lead exposure while residing at 2525 Oswego Avenue."

On 13 November 2012, Dr. Sundel was deposed at the behest of Respondent. His testimony established that he was well-read on the literature related to lead poisoning and its harmful effects on young children, but revealed that he had never studied or treated directly in his practice an individual with lead-based poisoning. Dr. Sundel did not examine Roy at any point during the litigation to that point. He claimed that it was not necessary to do so due to the documented evidence of Roy's neurological impairments adduced by Dr. Hurwitz after his personal evaluation of Roy.

Roy retained also Dr. Robert K. Simon, Ph.D., an industrial hygienist, who opined in a 2 June 2012 report that 2525 Oswego Avenue (owned by the Dackmans at the relevant time) was the source of Roy's exposure to lead-based paint. As with Dr. Sundel, Dr. Simon based his opinion on the record and the documents provided to him by Petitioner's counsel. Dr. Simon had "specific training, experience and certification in the areas of lead paint inspections and lead risk assessment including in the State of Maryland." After reviewing the information provided about Roy's residences, Dr. Simon stated that it was his opinion

On 2 January 2013, the Dackmans filed a Motion to Exclude Plaintiff's Experts and a companion Motion for Summary Judgment, arguing that Roy's "experts, Dr. Sundel and Dr. Simon, should be precluded from testifying as to the source of [Roy]'s alleged injuries as they lack both qualifications and factual basis required by Md. Rule 5-702." On 20 February 2013, the Circuit Court (Judge Carrion presiding) conducted a hearing and denied the Dackmans' motion, finding both witnesses qualified under Md. Rule 5-702. Judge Carrion stated relevantly that "a doctor may testify as to medical matters outside his/her area of expertise," acknowledging the well-established Maryland standard that a medical expert witness "need not be a specialist in order to be competent to testify on medical matters," citing Wantz v. Afzal, 197 Md.App. 675, 685, 14 A.3d 1244, 1250 (2011) (quotations omitted). The Circuit Court, at this time, noted that the Dackmans' objections to the admission of Dr. Sundel as an expert arose primarily due to his "purported unfamiliarity with lead paint poisoning and lack of [direct] knowledge as to the source of [Roy's] exposure." In keeping with then extant precedent from the Court of Special Appeals and this Court, the Circuit Court concluded that "[o]bjections attacking an expert's training, expertise or basis of knowledge go to the weight of the evidence and not its admissibility." Baltimore Gas & Elec. Co. v. Flippo, 112 Md.App. 75, 98, 684 A.2d 456, 467 (1996), aff'd 348 Md. 680, 705 A.2d 1144 (1998).

Following Judge Carrion's ruling, the Court of Special Appeals filed an opinion in City Homes, Inc. v. Hazelwood, 210 Md.App. 615, 63 A.3d 713, cert. denied sub nom. Hazelwood v. City Homes, 432 Md. 468, 69 A.3d 476 (2013), which spoke to Dr. Sundel's qualifications on the record of a separate lead paint suit. In that opinion, following a review of the record, the Court of Special Appeals held with respect to Dr. Sundel's "qualifications . . . that, although he is a board-certified pediatrician licensed to practice medicine in Maryland, he has not received any specialized training nor does he have any experience in treating children with lead poisoning or in identifying the source of a child's lead exposure." Hazelwood, 210 Md.App. at 684, 63 A.3d at 754. Due to these deficiencies, the Court of Special Appeals determined that Dr. Sundel was not qualified to testify "as an expert with a concentration in childhood lead poisoning, or to offer an opinion as to the source of [a child's] lead exposure or as to causation." Id.

Catching the Hazelwood train, the Dackmans renewed their Motion to Exclude Expert Witnesses and Motion for Summary Judgment. In an effort to rehabilitate Dr. Sundel in light of Hazelwood, Roy filed an affidavit of the doctor wherein he endeavored to respond to the specific criticisms in Hazelwood of his qualifications and to advance a more specific foundation than perhaps had been demonstrated in Hazelwood for his relevant bases to testify in Roy's case. On 6 May 2013, the Circuit Court (Judge Peters presiding) conducted an additional hearing to rule on the renewed motions. The following day, the Circuit Court granted the Dackmans' motion for summary judgment, stating that Dr. Sundel was not qualified to provide an expert opinion as to source of lead exposure or to medical causation. In reaching that ruling, Judge Peters did not exclude Dr. Simon as an expert witness as to source of Roy's lead poisoning nor comment on whether Roy's ability to establish the source of the lead poisoning could be proven through adequate circumstantial evidence. Based on the exclusion of Dr. Sundel, however, the Circuit Court found that "without the testimony of a medical expert, Roy could not demonstrate `the link between [his elevated] blood lead levels and the injuries allegedly suffered by the plaintiff.'" Roy v. Dackman, 219 Md.App. 452, 467, 101 A.3d 448, 457 (2014) (alterations in original).

Roy appealed timely to the Court of Special Appeals, which affirmed in a reported opinion. Roy v. Dackman, 219 Md.App. 452, 101 A.3d 448 (2014). The Court of Special Appeals held that the Circuit Court

We issued a writ of certiorari, on Roy's petition, Roy v. Dackman, 441 Md. 217, 107 A.3d 1141 (2015), to consider the following questions:

For reasons we shall explain, we disagree with the Court of Special Appeals that Dr. Sundel was not qualified to testify in this lead paint poisoning case as to medical causation. Our agreement with the intermediate appellate court as to excluding Dr. Sundel as an expert witness as to source of the lead poisoning (for which element of the claim, Petitioner had another witness—Dr. Simon—and arguably circumstantial evidence11) does not change the necessity for reversal here.12

II.

Standard of Review

We have explained "the admissibility of expert testimony is a matter largely within the discretion of the trial court, and its action in admitting or excluding such testimony will seldom constitute a ground for reversal." Bryant v. State, 393 Md. 196, 203, 900 A.2d 227, 231 (2006) (internal quotations omitted). A circuit court's decision to exclude a witness will be reversed only if there is a clear abuse of discretion. Id.; see also Samsun Corp. v. Bennett, 154 Md.App. 59, 67, 838 A.2d 381, 386 (2003).

A circuit court's grant of summary judgment, however, is a question of law that is reviewed de novo for legal correctness. Piscatelli v. Van Smith, 424 Md. 294, 305, 35 A.3d 1140, 1146 (2012). Under Md. Rule 2-501(f), summary judgment will be granted when "there is no genuine dispute as to any material fact and. . . the party in whose favor judgment is entered is entitled to judgment as a matter of law." We review the grant of a motion for summary judgment to determine whether "there is a dispute as to a material fact sufficient to provide an issue to be tried." Charles Cnty. Comm'rs v. Johnson, 393 Md. 248, 263, 900 A.2d 753, 762 (2006) (quotations omitted). We "review independently the record to determine whether the parties generated a dispute of material fact and, if not, whether the moving party was entitled to judgment as a matter of law." Tyler v. City of Coll. Park, 415 Md. 475, 499, 3 A.3d 421, 434 (2010) (citing Charles Cnty. Comm'rs, 393 Md. at 263, 900 A.2d at 762). This review is done in "the light most favorable to the non-moving party and [we] construe any reasonable inferences that may be drawn from the well-plead facts against the moving party." Id.

As noted recently in Hamilton v. Kirson, 439 Md. 501, 521 n. 11, 96 A.3d 714, 726 n. 11 (2014), reconsideration denied (Aug. 27, 2014), typically, when a case involves the grant of summary judgment on the basis that the expert witness "lacks a sufficient factual basis of admissible facts and the admissible evidence (if any) is insufficient independently to prove causation, the circuit court is making a decision on the admissibility of the expert's testimony as part of its summary judgment decision and, thus, is making a legal decision." We review those cases "on appeal without deference, as the grant of all summary judgment motions are." Id.

Because we are reviewing the factual finding of qualifications and predicate competence, as opposed to the legal conclusion about the sufficiency of Dr. Sundel's factual basis, we will review the decision for an abuse of discretion. This case differs from the standard set forth in Hamilton because the basis for exclusion of Dr. Sundel was the factual finding that he was not qualified due to his inexperience with lead poisoning medicine and science, not the legal decision to grant summary judgment in the absence of any admissible evidence of medical causation. Therefore, we will only reverse the Circuit Court's decision to exclude Dr. Sundel if we conclude there was a clear abuse of discretion, which we find to be the case here.

III.

A. The Parties' Contentions as to Dr. Sundel's Qualifications

Roy contends that the Court of Special Appeals erred when it affirmed the Circuit Court's decision to exclude Dr. Sundel as an expert on both source of lead exposure and medical causation. Roy contends that Dr. Sundel, a board-certified pediatrician, based on his knowledge, skill, and training, was qualified to provide expert testimony as to both elements. This failure to admit Dr. Sundel as an expert on both source and medical causation resulted, as Petitioner sees it, in the improper grant of summary judgment to the Dackmans.

The Dackmans respond that the Court of Special Appeals was correct to affirm the exclusion of Dr. Sundel due to his lack of experience with the treatment and identification of lead poisoning in children (or anyone else for that matter). The Dackmans dispute that the Court of Special Appeals created a new requirement, i.e., that in order to testify as a medical expert, one must be a specialist. Rather, as Respondent sees it, the intermediate appellate court's opinion required merely that Dr. Sundel needed only some expertise in the field of lead poisoning, which he lacked.

B. The Law

Under Maryland Rule 5-702, expert testimony

These three factors have been plumbed generally and well in many appellate opinions of our appellate courts.

To satisfy the first requirement, we have explained that "a witness may be competent to express an expert opinion if he [or she] is reasonably familiar with the subject under investigation, regardless of whether this special knowledge is based upon professional training, observation, actual experience, or any combination of these factors." Radman v. Harold, 279 Md. 167, 169, 367 A.2d 472, 474 (1977). Fundamentally, an expert witness's opinion is expected to "give the jury assistance in solving a problem for which their equipment of average knowledge is inadequate." Id.

To qualify as an appropriate medical expert under Md. Rule 5-702(2), a doctor is not required to have ever performed the surgery in question or even to have observed that specific patient who may be the plaintiff. See Hazelwood, 210 Md.App. at 678, 63 A.3d at 750 (citing Radman, 279 Md. at 170, 367 A.2d at 472). Inquiries about a doctor's personal experience performing a certain procedure goes to the weight, not the admission vel non, of the doctor's testimony. Admission of a doctor's testimony is a threshold question, specifically as to which we have observed:

Radman, 279 Md. at 171, 367 A.2d at 474-75 (citations omitted). Therefore, basing an opinion solely on "medical" literature and personal observation does not justify necessarily excluding a witness from qualifying as a medical causation expert:

Hazelwood, 210 Md.App. at 677, 63 A.3d at 749-50 (citing Radman, 279 Md. at 169-70, 367 A.2d at 472).

An adequate factual basis for expert testimony is required under Md. Rule 5-702(3) so that the testimony "constitutes more than mere speculation or conjecture." Exxon Mobil Corp. v. Ford, 433 Md. 426, 478, 71 A.3d 105, 136 as supplemented on denial of reconsideration, 433 Md. 493, 71 A.3d 144 (2013) (citing Giant Food, Inc. v. Booker, 152 Md.App. 166, 182-83, 831 A.2d 481, 490 (2003)). Accordingly, Md. Rule 5-702(3) "consists of two distinct sub-factors. It is first required that the expert have available an adequate supply of data with which to work. It is then required that the expert employ a reliable methodology in analyzing that data." CSX Transp., Inc. v. Miller, 159 Md.App. 123, 189, 858 A.2d 1025, 1063 (2004). With respect to this requirement, our intermediate appellate court brethren have said that a "factual basis `may arise from a number of sources, such as facts obtained from the expert's first-hand knowledge, facts obtained from the testimony of others, and facts related to an expert through the use of hypothetical questions.'" Taylor v. Fishkind, 207 Md.App. 121, 143, 51 A.3d 743, 756 (2012) (citing Sippio v. State, 350 Md. 633, 653, 714 A.2d 864, 874 (1998)).

Thus, under Md. Rule 5-702, an expert witness who proposes to testify on medical injury must base his or her opinion on reliable knowledge, skill, and experience, but is not required necessarily to be a specialist. It may well be that a "specialist" who testifies as to certain opinions may receive greater weight by the fact-finder than his or her competing non-specialist, but that is not resolved ordinarily as a threshold matter by a judge. Cross-examination is the usual crucible for persuading the fact-finder which witness merits the greater weight. "For expert testimony to be admissible, his or her conclusions must be based on a sound reasoning process explaining how the expert arrived at those conclusions." Exxon Mobil Corp., 433 Md. at 483, 71 A.3d at 139.

IV.

Analysis

Although Dr. Sundel may not be the most qualified expert witness on medical causation, a court's concern at the summary judgment stage is whether his testimony is admissible. Based on Dr. Sundel's background, affidavit, and deposition (which create a better foundation than was available in the record in Hazelwood), it is apparent that he is competent, under the standards set forth in Md. Rule 5-702, to testify as an expert as to medical causation here. The Circuit Court abused its discretion, therefore, in finding him unqualified to testify as to medical injury.13 Nevertheless, we do agree that, with no personal knowledge and his reliance on circumstantial evidence as to how and where Roy was exposed to lead paint, Dr. Sundel was not shown to be competent on this record to testify as to the source of Roy's exposure. Thus, it was not an abuse of discretion for the Circuit Court to exclude his testimony on that element.

A. Source of Lead Exposure

In Taylor v. Fishkind, 207 Md.App. 121, 51 A.3d 743 (2012), the plaintiff identified a pediatrician, Dr. Henri Merrick, as one of her expert witnesses. The basis for designating Dr. Merrick as an expert was explained as:

Taylor, 207 Md.App. at 126, 51 A.3d at 746. Her report concluded that the plaintiff was exposed at two separate properties, based on: "the age of the dwellings, the described conditions of the first dwelling, the detection of lead in an exterior window apron of this first dwelling and [the plaintiff's] blood lead levels while living at each dwelling." Taylor, 207 Md. App. at 130, 51 A.3d at 748.

The circuit court granted summary judgment to the defendant in Taylor because the plaintiff relied solely on Dr. Merrick's testimony, which lacked a factual basis to establish, within a reasonable degree of medical certainty, that the subject properties were the source of lead. Taylor, 207 Md.App. at 136, 51 A.3d at 752. Dr. Merrick lacked a sufficient factual basis as to the source of lead because her opinion that the interior of the subject property "contained lead-based paint [was] only supported by the age of the house and the presence of lead on one component of the exterior of the house." Taylor, 207 Md.App. at 142, 51 A.3d at 755. Dr. Merrick admitted that she could not rule out the possibility of other sources. Id. The reliance on scant circumstantial evidence alone was not enough to allow her to opine as to the source of lead beyond mere speculation.

In 2013, we decided Ross v. Hous. Auth. of Baltimore City, 430 Md. 648, 63 A.3d 1 (2013), which presented facts similar to the present case. We held that the circuit court did not abuse its discretion when it excluded the expert testimony of a pediatrician who was retained to "establish the defendant's building as the source of the plaintiff's lead exposure and elevated blood lead levels." Ross, 430 Md. at 651, 63 A.3d at 2.

The proposed expert, Dr. Jacalyn Blackwell-White, a pediatrician with over 20 years-experience, who provided "an opinion on whether [the plaintiff] had been exposed to toxic lead levels and whether that exposure had caused brain impairment." Ross, 430 Md. at 656, 63 A.3d at 5. Dr. Blackwell-White's review of the plaintiff's medical records and information relating to the two subject properties led her to conclude that the plaintiff "had been exposed to lead-based paint at both residences, that such exposure `resulted in sustained toxic blood levels' during her early developmental years, and that the end result would be life-long neuropsychological impairment." Ross, 430 Md. at 656, 63 A.3d at 5-6.

Even though Dr. Blackwell-White's medical practice included the identification and treatment of childhood lead poisoning patients, she admitted that "she was not capable of definitively determining the source of lead exposure [and that] she was merely assessing risks." Ross, 430 Md. at 657, 63 A.3d at 6. She concluded that the subject property was the source of lead exposure because of:

Ross, 430 Md. at 659, 63 A.3d at 7-8. The circuit court excluded only Dr. Blackwell-White's testimony as to the source of the plaintiff's lead exposure because it found that source and medical causation were two distinct questions. Ross, 430 Md. at 662, 63 A.3d at 9.

In Ross, we agreed with the exclusion of Dr. Blackwell-White's testimony as to source of lead exposure. We reasoned that her opinion would not assist the trier of fact as she

Ross, 430 Md. at 663, 63 A.3d at 10. Her opinion as to source was excluded properly because it was based only on an assessment of risks and an assumption of the presence of lead paint in the subject property.

For similar reasons, we agree that Dr. Sundel was not competent to testify as to the source of Roy's lead exposure. Dr. Sundel's proposed opinion falls victim to the same problems as those discussed in Taylor and Ross. As a board-certified pediatrician, his reliance on circumstantial evidence alone is not enough for him to be deemed competent as an expert on the source of lead. Much like Dr. Merrick in the Taylor case, Dr. Sundel's conclusion was based solely on scant circumstantial evidence, including the age of the home and exterior tests of the paint on the dwelling at 2525 Oswego Avenue. Although we have held that a lead poisoning case may succeed grounded on suitable circumstantial evidence as to source, Hamilton, 439 Md. at 527, 96 A.3d at 730, it is not enough for an expert to conclude that a certain property is the source of the child's exposure to lead when other probable sources have not been eliminated. Compare Dow v. L & R Properties, Inc., 144 Md.App. 67, 75-76, 796 A.2d 139, 143-44 (2002) (Even without expert testimony, the circumstantial evidence was sufficient to survive summary judgment because "[i]f believed, the evidence offered by appellants in opposition to the motion for summary judgment could establish that the chipping and peeling paint inside 1237 Myrtle Avenue was the only possible source of [the child's] lead poisoning.").

Akin to Dr. Blackwell-White's proffered testimony in Ross, Dr. Sundel's tendered conclusion that 2525 Oswego Avenue was the source of Roy's exposure to lead-based paint did not rule out other probable sources. There is no discussion in the record of Dr. Sundel's methods to eliminate other environmental sources of lead exposure. His conclusion that 2525 Oswego Avenue was a substantial contributing source of Roy's lead exposure appears to be based solely on the assumption that a child's home is the "most probable source of elevated blood lead levels `until proven otherwise,' particularly if the house was built before 1970." Ross, 430 Md. at 660, 63 A.3d at 8. We concluded in Ross, due the variety of probable sources of the plaintiff's lead exposure, that Dr. Blackwell-White's conclusion as to source of lead exposure was "as likely to confuse as to assist a jury." Ross, 430 Md. at 664, 63 A.3d at 10.14

B. Medical Causation

In Ross, the circuit court concluded that "Dr. Blackwell-White was qualified to testify as an expert in pediatrics and childhood lead-poisoning." Ross, 430 Md. at 662, 63 A.3d at 9. We pointed out that, based on the record in Ross, it appeared that "the only portion of Dr. Blackwell-White's testimony that was excluded was her opinion that the Payson Street home was the source of [the plaintiff's] lead exposure during the relevant time period that led to enhanced blood lead levels." Id. Even after she was considered competent to testify as to medical causation, Dr. Blackwell-White "testified at one point that she was merely identifying `potential risk' and could not make any statement as to causation with certainty." Ross, 430 Md. at 664, 63 A.3d at 10.

Dr. Blackwell-White was deemed competent to testify as to medical causation based solely on her qualifications and experience as a pediatrician with 20 years in practice.15 Within her lead paint victim practice, Dr. Blackwell-White relied on recommendations from the Centers for Disease Control, the American Academy of Pediatrics, the Maryland Department of the Environment, and numerous other academic sources. Ross, 430 Md. at 658, 63 A.3d at 6-7. Effectively, her testimony established that this research and her methods of identifying lead exposure risks were considered "best practices" and "generally accepted in the pediatric medical community." Ross, 430 Md. at 657, 63 A.3d at 6. Here, Dr. Sundel has similar qualifications, albeit no direct hands-on experience with treating lead poisoning patients.

Respondents rely on Hazelwood to illustrate the deficiencies of Dr. Sundel's qualifications here. There are material differences, however, between the records in the two cases as to his qualifications. The Court of Special Appeals concluded in Hazelwood that Dr. Sundel was not competent to testify as a medical expert under Maryland Rule 5-702 because he had "never testified as an expert in a lead paint poisoning case . . . and [he] acknowledged that he [wa]s not a certified lead risk assessor." Hazelwood, 210 Md.App. at 685, 63 A.3d at 754. Additionally, Dr. Sundel was deemed unqualified on that occasion because he had not published or lectured on the topic of lead paint poisoning, he was not a board-certified psychologist, and he did not administer or interpret IQ tests in his practice. Hazelwood, 210 Md.App. at 685-86, 63 A.3d at 754-55.

In Hazelwood, the Court of Special Appeals concluded that Dr. Sundel lacked "specialized knowledge concerning childhood lead poisoning, and specifically, the determination of the source of a child's lead exposure and causation." Hazelwood, 210 Md.App. at 686, 63 A.3d at 755. This reasoning is overly demanding because the standard set forth in Md. Rule 5-702 is not that an expert have "specialized knowledge." The Rule requires only that the "witness is qualified as an expert by knowledge, skill, experience, training, or education" because the purpose of expert witness testimony is to assist the finder of fact, in this case, a jury composed likely of lay persons. See Md. Rule 5-702(1).

A major difference between the factual record in Hazelwood and the one presented here relates to Dr. Sundel's respective preparation for rendering an opinion. The record in Hazelwood lent itself to the conclusion that Dr. Sundel read articles generally about lead paint poisoning, but had not studied intensively the written materials. He was admitted by the Circuit Court in Hazelwood as "an expert pediatrician, especially with the concentration or including the concentration on his research and experience in childhood lead paint because his testimony is reflective of his special knowledge," a conclusion for which the Court of Special Appeals failed to find support in that record. Hazelwood, 210 Md.App. at 687, 63 A.3d at 755 (emphasis added).

Here, in his fourteen-page affidavit submitted post-Hazelwood, Dr. Sundel endeavored to be more specific and shore-up the supposed deficiencies in his qualifications. He attested that he had read extensively on lead paint poisoning in adolescents: "Since the Hazelwood trial, I continue to review all new published literature and public policy statements from the Center for Disease Control that concern childhood lead poisoning." Although conceding that he was not a "Certified Lead Risk Assessor," he maintained that, in his position as a board-certified pediatrician, he was

Dr. Sundel noted that in Hazelwood he "did not have a report from Dr. Simon or any other professional lead risk assessor and toxicologist."

He maintained that it is part of his normal course of business to consult psychologists or neurologists to determine if exposure to any environmental toxin, including lead, could have resulted in brain damage, cognitive defects or physical symptoms exhibited by a patient. As part of these consultations, Dr. Sundel would work with a pediatric neurologist to determine "diagnosis options and treatment options and to assist with a determination of etiology." Dr. Hurwitz's report of his four hour, in-person evaluation of Roy was one of the many reports that Dr. Sundel claimed to have reviewed in the present case. Although Dr. Sundel did not work directly with Dr. Hurwitz, the report provided Dr. Sundel with Dr. Hurwitz's interpretation of his testing and additional relevant background on Roy. Dr. Sundel attested further in his affidavit that he has read numerous articles from various sources (see fn. 10 infra), including the CDC, the American Academy of Pediatrics, and the National Institutes of Health. Dr. Sundel also relied on a study conducted by Bruce Lanphear, which has been cited to and discussed extensively by other studies employing similar tests relating to IQ loss and childhood lead poisoning.16

"Under Maryland law, as a general proposition, in order to qualify as an expert, the witness need not possess special knowledge if he or she is generally conversant with the subject of the controversy." Samsun Corp., 154 Md.App. at 68, 838 A.2d at 386. Dr. Sundel's academic and experiential qualifications include a three year pediatric residency in New York, a two year pediatric fellowship at Johns Hopkins University Hospital, and more than 20 years in practice. With this experience and as a board-certified pediatrician, Dr. Sundel was shown on this record to possess a sufficient background from which to provide an opinion as to the injuries claimed to have been suffered by Roy as the result of alleged exposure to lead. Whether a jury will find his testimony persuasive will depend, in large measure, on the effectiveness of Respondent's cross-examination and a comparison/weighing by the jury against Respondent's competing witness(es)' testimony.

V.

Conclusion

As we held in Ross, medical causation and source of lead exposure are distinct questions which generally are the subject of expert witness testimony in childhood lead-based paint poisoning cases. In Ross, we indicated that because "the Circuit Court's ruling with regard to Dr. Blackwell-White purported only to exclude her testimony as to the source of the lead exposure, the remainder of her testimony, including foundational and background information on lead poisoning" would still be considered with the other circumstantial evidence, "which presumably would foreclose a grant of summary judgment." Ross, 430 Md. at 670-71, 63 A.3d at 14.

Similarly, in the present case, with the arguable presence in the on-deck circle of Dr. Simon, an industrial hygienist and toxicologist, to speak to the source of lead, and our decision that Dr. Sundel is competent to testify as a medical causation expert, it was improper for the Circuit Court to grant summary judgment when it did. Therefore, we reverse the judgment of the Court of Special Appeals and direct the remand of the case for further proceedings in the Circuit Court for Baltimore City.17

JUDGMENT OF THE COURT OF SPECIAL APPEALS REVERSED; CASE REMANDED TO THAT COURT WITH DIRECTIONS TO REVERSE THE JUDGMENT OF THE CIRCUIT COURT FOR BALTIMORE CITY AND REMAND THE CASE TO THE CIRCUIT COURT FOR FURTHER PROCEEDINGS CONSISTENT WITH THIS OPINION. COSTS IN THIS COURT AND THE COURT OF SPECIAL APPEALS TO BE PAID BY RESPONDENTS.

BATTAGLIA and McDONALD, JJ., dissent.

McDONALD, J., dissenting in part, in which BATTAGLIA, J. joins.

In applying an "abuse of discretion" standard, this Court has often said that an abuse of discretion occurs "where no reasonable person would take the view adopted by the [trial] court, or when the court acts without reference to any guiding rules or principles . . . when [the decision] is well removed from any center mark imagined by the reviewing court and beyond the fringe of what that court deems minimally acceptable." E.g., Nash v. State, 439 Md. 53, 67, 94 A.3d 23 (2014) (quoting North v. North, 102 Md.App. 1, 648 A.2d 1025 (1994)) (internal citations and quotation marks omitted).

When a trial court ruling is assessed on an abuse of discretion standard, this means that there is not necessarily one right answer, nor is the trial court required to come up the best answer or the answer preferred by the appellate court.

If the Circuit Court in this case had determined that expert testimony by Dr. Sundel on medical causation would be of assistance to the jury and that Dr. Sundel was qualified to provide such testimony for the reasons set forth in the Majority opinion, I would have concluded that the court had not abused its discretion.

But that does not mean that Circuit Court abused its discretion in coming to a different conclusion. The Circuit Court carefully considered very recent appellate decisions concerning expert witnesses in lead paint cases, including one in which the Court of Special Appeals specifically held that Dr. Sundel was not qualified to testify as an expert on medical causation.1 The Circuit Court did not blindly adopt the conclusion of the intermediate appellate court, but explicitly assessed the asserted additions to Dr. Sundel's qualifications since the prior case and the fact that he still had no hands-on experience with victims of lead paint poisoning in deciding to apply the holding of the Court of Special Appeals.

I do not believe it was an abuse of discretion for the Circuit Court to conclude that the enhancements in Dr. Sundel's qualifications from the prior case—his longer reading list and his apparently better preparation for pre-trial depositions—did not convert him into a qualified expert on medical causation in this case. It cannot be said that "no reasonable person" would take that view, that the court acted without reference to any guiding principles, or that its answer was "beyond the fringe" of what would be minimally acceptable.

In my view, the answer provided by the Majority opinion as to whether Dr. Sundel should be allowed to testify on medical causation in lead paint cases is probably the better answer, but that does not mean that the Circuit Court here abused its discretion in ruling as it did. Indeed, it seems odd to hold that a Circuit Court "abused its discretion" by following a very recent appellate decision precisely on point.

This case may illustrate the tension that an appellate court faces when it seeks to provide guidance for the future by indicating a better answer and its limited role when applying an abuse of discretion standard.

Judge BATTAGLIA advises that she joins this dissent.