(concurring). Although harmless in this instance, I am of the view that the cross-examination of defendant on *601the basis of the statements of Ronnie Lapan and Kevin Lawless was improper and consider the issue worthy of discussion and comment.
As a general proposition, of course, a defendant who testifies places himself in the same position as any other witness, including exposure to cross-examination on matters affecting his credibility (see, e.g., People v Betts, 70 NY2d 289). It is likewise true that for impeachment purposes, evidence which would otherwise be inadmissible may be utilized in cross-examination upon a finding that defendant, through his testimony, “opened the door” to its use. The rationale for this rule is the principle that the shield protecting a defendant from use of the material in the first instance “ ‘cannot be perverted into a license to use perjury by way of a defense’ ” (People v Fardan, 82 NY2d 638, 646, quoting Harris v New York, 401 US 222, 226).
These principles are not without limitations, however fundamental they may be. First and foremost, the impeachment evidence must have probative value. Thus, in People v Fardan (supra) the Court of Appeals cautioned that “trial courts must exercise care to assure that the precluded evidence is not merely related to the testimony but in fact refutes the testimony given on direct” (id., at 646 [emphasis supplied]). Most commonly, this evidence will take the form of prior convictions whose nature is relevant to credibility or which refute a defendant’s denial (see, e.g., People v Rodriguez, 85 NY2d 586, 591-592; People v Fardan, supra, at 645-646). Moreover, even where such evidence has probative value, it should not be admitted unless its probative value sufficiently outweighs its prejudicial impact (see, People v Dokes, 79 NY2d 656, 661).
The material at issue here is questionable under both criteria. Initially, its probative value is marginal. Just as a witness may not be impeached on the basis of an arrest or accusation of prior criminal conduct because it has no probative value (see, Prince, Richardson on Evidence § 6-409, at 397 [Farrell 11th ed]; see also, People v Grant, 234 AD2d 475, 476; People v Colas, 206 AD2d 183, 186-187, lv denied 85 NY2d 907; People v Gottlieb, 130 AD2d 202, 207, mod 132 AD2d 498), neither should unsubstantiated, hearsay accusations be invested with evidentiary significance. Testimony which arguably “opens the door” for impeachment does so only for evidence that truly refutes it (see, People v Garcia, 169 AD2d 358, 363, lv denied 79 NY2d 857; People v Steele, 168 AD2d 937, 938, lv denied 77 NY2d 967). Furthermore, while a defendant may be cross-examined about immoral, criminal or vicious acts even though *602such acts did not result in convictions, it is elementary that such questions must be asked in good faith and with a reasonable basis in fact (see, Prince, Richardson on Evidence § 6-406, at 389 [Farrell 11th ed]; see also, People v Duffy, 36 NY2d 258, 262, mod 36 NY2d 857, cert denied 423 US 861; People v Steele, supra, at 938; People v Booker, 134 AD2d 949, 949-950, lv denied 70 NY2d 953; People v Delacruz, 127 AD2d 887, 888-889; People v Simpson, 109 AD2d 461, 464, appeal dismissed 67 NY2d 1026).* Thus, measuring its slight probative worth against the potential for undue prejudice, particularly in view of its similarity to the crimes with which defendant was charged and the excessive number of incidents to which it referred (see, People v Turner, 247 AD2d 821; People v Santiago, 47 AD2d 476, 478-480), the evidence should not have been used.
Ordered that the judgment is affirmed.
The question of what constitutes such good faith or “reasonable basis in fact” divided the Court of Appeals in People v Alamo (23 NY2d 630, cert denied 396 US 879) and has received scant judicial attention since (see, People v Simpson, 109 AD2d 461, 471, appeal dismissed 67 NY2d 1026). While the dissent in People v Alamo argued for a standard requiring that the factual truth of the matter be established, the majority held that the cross-examiner must possess “some reasonable basis for believing the truth” of the matter upon which the witness is questioned (id., at 633).