OPINION OF THE COURT

JONES, J.

Defendant was charged with numerous offenses, including three counts of arson in the first degree (Penal Law § 150.20), in connection with two fires set five days apart in a four-story apartment building located at 408 Greene Avenue in Brooklyn, New York. The evidence adduced at trial established that defendant, who did not own the building, engaged in a scheme to profit from its illegal sale. Defendant gained control of the property by means of a forged and fraudulently notarized deed. He then contracted to sell it to a third party for $300,000. Pursuant to a clause in the sales contract, the property was to be delivered "vacant and free of leases or tenancies." To that end, defendant, on two occasions, paid others to set fires in the building to drive the tenants out. Defendant was convicted, upon a jury verdict, of three counts of arson in the first degree, one count relating to a fire set on May 25, 2004 (expectation of pecuniary profit), and the other two counts relating to a fire set on May 30, 2004 (expectation of pecuniary profit and use of an incendiary device).

On appeal, defendant argued that the prosecutor repeatedly violated the trial court's Molineux rulings (see People v Molineux, 168 N.Y. 264 [1901] [for Molineux rule]; People v Allweiss, 48 N.Y.2d 40, 46-48 [1979] [for summary of principles related to Molineux rule]) by eliciting evidence of an uncharged arson attempt and of his prior bad acts and associations—the elicited testimony linked defendant to violence, guns, the Nation of Islam, and a violent motorcycle gang. In defendant's view, the prosecutor's repeated violations of the court's Molineux rulings cumulatively denied him the right to a fair trial (see People v Calabria, 94 N.Y.2d 519, 522 [2000]).

Defendant further argued that the elicited expert testimony concerning the origins of the fires was inadmissible under People v Grutz (212 N.Y. 72, 82 [1914] ["The physical facts" of an arson are always "so simple that they can be readily understood when properly described, and it is then for the jury to draw the appropriate conclusion," without guidance of expert opinion]) and People v Narrod (23 A.D.3d 1061, 1062 [4th Dept 2005] [it was error to allow an "arson investigator to testify that he had ruled out accidental causes of the fire"])1 According to defendant, the experts' improper testimony invaded the jury's province and denied him the right to a fair trial.

The Appellate Division affirmed the convictions, stating that any error concerning the contested testimony was harmless (74 A.D.3d 995, 995 [2d Dept 2010]). A Judge of this Court granted defendant leave to appeal and we now affirm.

Although, as the People concede, certain questions asked by the prosecutor at trial clearly violated the trial court's Molineux rulings, the contested testimony elicited, on the whole, was not significant. That is, if defendant was prejudiced at all, such prejudice was minimal. Each time after defendant moved for a mistrial based on an alleged violation of the court's Molineux rulings, the trial court, in its discretion, considered the arguments of the parties, concluded that what happened did not rise to the level of a mistrial and, in certain instances, provided further instruction to counsel to refrain from making statements regarding improper topics. For example, at the conclusion of the prosecutor's opening statement, defendant moved for a mistrial, arguing, inter alia, that the prosecutor's references to the Nation of Islam and Muslims were intended to inflame and prejudice the jury. After ruling that a mistrial was not warranted, the court told the prosecutor to "stay focused" and to avoid the appearance of stereotyping certain individuals just because they are members of the Nation of Islam and/or Muslims.

The trial court also took steps to minimize the impact of arguably improper testimony or prosecutorial statements during the trial. For example, after the prosecutor made conclusory statements of fact during his opening statement, the court sustained defense counsel's objection and reminded the jurors in no uncertain terms that "what counsel says is not evidence in the case. Rather, you may consider the opening statement as a preview or an outline of what counsel believes the evidence will prove in this case."

In any event, to the extent any evidence subject to the trial court's Molineux rulings was improperly admitted, such error was harmless (see People v Crimmins, 36 N.Y.2d 230, 240-242 [1975]). The evidence against defendant, from his own taped admissions, and testimony of the individual who set the first fire at defendant's behest, overwhelmingly established defendant's guilt of the crimes charged. Further, there was no reasonable possibility or significant probability that the improper questions and elicited references to defendant's bad acts and negative associations affected the jury's verdict, or that the absence of such errors would have led to an acquittal.

Defendant's second argument—that the expert testimony, ruling out accidental and natural causes of the fires and concluding that one of the fires was intentionally set, invaded the jury's province—is equally unavailing. At the outset, we consider the rule set forth in Grutz prohibiting expert testimony concerning whether a fire was intentionally set. This prohibition occurs as dictum in an opinion written in 1914—at a time when fire investigations involved far less technical expertise than they do today. Nevertheless Grutz is still frequently cited for the proposition that an expert may not invade the province of the jury by testifying that a fire was intentionally set2 or that the facts are "consistent" with an intentionally set fire.3 It has continued to be cited even after Appellate Division panels have held that an arson expert may testify to a reasonable degree of scientific certainty that, based on the expert's investigations, all possible natural and accidental causes of the fire had been eliminated4— thus eliminating all but intentional causes.

The result is that the law in New York is at once confusing and anomalous. As the Connecticut Supreme Court has recently noted,

We now put the Grutz proposition to rest. New York has a well-established body of case law concerning the admissibility and limits of expert testimony, that should be brought to bear in deciding what an arson expert may tell the jury in a particular case. "The guiding principle is that expert opinion is proper when it would help to clarify an issue calling for professional or technical knowledge, possessed by the expert and beyond the ken of the typical juror" (De Long v County of Erie, 60 N.Y.2d 296, 307 [1983] [citations omitted]; see People v Taylor, 75 N.Y.2d 277, 288 [1990] [same]). Moreover, this principle applies to testimony regarding both "the ultimate questions and those of lesser significance" (People v Cronin, 60 N.Y.2d 430, 432-433 [1983]).

Although, in deciding whether expert testimony is admissible, courts must determine whether "the potential value of the evidence is outweighed by the possibility of undue prejudice to the defendant or interference with the province of the jury" (People v Bennett, 79 N.Y.2d 464, 473 [1992]), "courts should be wary not to exclude such testimony merely because, to some degree, it invades the jury's province" (People v Lee, 96 N.Y.2d 157, 162 [2001]). "Expert opinion testimony is used in partial substitution for the jury's otherwise exclusive province which is to draw `conclusions from the facts.' It is a kind of authorized encroachment in that respect" (People v Jones, 73 N.Y.2d 427, 430-431 [1989] [citation omitted], quoting Cronin, 60 NY2d at 432). Obviously, expert testimony would not generally be admissible in a case where the fire's cause is not in question.

Here, because the evidence adduced at trial conclusively established, apart from the expert testimony, that the subject fires were intentionally set, it can be argued that the admission of expert testimony was largely unnecessary. In any event, any error was harmless, because the evidence of defendant's guilt was overwhelming and there was no significant probability that the jury would have acquitted defendant without the expert testimony (see Crimmins, 36 NY2d at 240-242).

Accordingly, the order of the Appellate Division should be affirmed.

Order affirmed.