OPINION OF THE COURT
Jones, J.The issues before this Court are whether Supreme Court abused its discretion by denying defendant’s request for the substitution of assigned counsel and by issuing a Sandoval ruling which permitted the prosecutor to refer to defendant’s prior drug-related felony convictions by naming the specific crimes, should he choose to testify. We hold that it did not.
On April 25, 2007, defendant was arrested for the sale of cocaine after detectives, assigned to the surveillance of drug *591activity in a particular area, observed defendant conduct two apparent drug transactions in front of a bar in Manhattan. The detectives first arrested the two individuals, who they allegedly saw give defendant money in exchange for drugs, and recovered crack cocaine from each of them. Upon defendant’s arrest, they discovered additional drugs in his back pocket. Defendant was charged with two counts of criminal sale of a controlled substance in the third degree, criminal possession of a controlled substance in the third degree, and criminal possession of a controlled substance in the fifth degree.
Prior to jury selection, defendant indicated that his former defense counsel “really botched up” and that he felt his present attorney was not “going to represent [him] to the best of his ability.”* Initially, defendant expressed that he and his attorney disagreed about how to proceed with pretrial motions. More specifically, he complained that counsel did not follow his request to renew a motion to dismiss the indictment based upon the testifying officers’ failure to state their prior experience and training before the grand jury. Counsel explained, however, that he indicated to defendant that the issue was preserved for appeal in the event that the motion court ruled incorrectly. According to defendant, he did “not feel comfort [able] going to . . . trial with this man.” The court warned that it would not continue to assign defendant different attorneys. After noting that the case was ready for trial, the court advised defendant that counsel was an able, competent and experienced criminal attorney. Defense counsel explained his preparation for defendant’s trial and that he had tried many observation sale cases. The court denied defendant’s request for the substitution of assigned counsel. Defendant however did not accept the court’s decision and continued to express that he did not want to go to trial with present counsel. The court further explained that it would not assign new counsel to him without a reason.
At the Sandoval hearing, the prosecutor sought to question defendant, if he chose to testify, concerning three prior felony drug convictions from 1994, 1995 and 2004, as well as a 2004 conviction for unlawfully carrying a gun. Defendant requested that the prosecution be restricted to referring to the convictions as felonies without indicating the offense. The trial court denied *592defendant’s request, but limited the prosecutor’s inquiry regarding the prior convictions to the type of crime, county and date of conviction. The court further advised that it would instruct the jury that the prior convictions are not evidence of defendant’s guilt in the present case. Defendant testified during pretrial proceedings and gave a different account of the events, specifically denying the possession of any drugs. Defendant did not testify at trial.
Defendant was convicted, upon a jury verdict, of the crimes charged in the indictment. On appeal, defendant argued, among other things, that the trial court erred in denying his application for substitution of assigned counsel and its Sandoval ruling constituted an abuse of discretion.
The Appellate Division “unanimously modified, on the law, to the extent of vacating the sentence and remanding for resentencing, and otherwise affirmed” (75 AD3d 420, 420-421 [1st Dept 2010]). It held that “[defendant failed to demonstrate good cause for the assignment of substitute counsel” and that the trial “court properly exercised its discretion” in its Sandoval ruling (id. at 421). A Judge of this Court granted defendant leave to appeal, and we now affirm.
Criminal defendants are guaranteed the right to effective representation by counsel under the Federal and State Constitutions (see US Const 6th Amend; NY Const, art I, § 6; see also People v Linares, 2 NY3d 507 [2004]; People v Baldi, 54 NY2d 137 [1981]). Moreover, our Constitution guarantees indigent defendants the right to assigned counsel (see People v Medina, 44 NY2d 199 [1978]; People v Koch, 299 NY 378, 381 [1949]). It is well-settled that “[t]he legal assistance provided must be ‘effective’ ” (Medina, 44 NY2d at 207). To ensure effective representation of assigned counsel, courts “must ‘carefully evaluate serious complaints about counsel’ ” (Linares, 2 NY3d at 510, quoting Medina, 44 NY2d at 207). To that end, when a defendant requests the assignment of new counsel, provided “good cause” exists, “a court is well advised to effect [such] change” (Medina, 44 NY2d at 207). “Good cause determinations are necessarily case-specific and therefore fall within the discretion of the trial court” (Linares, 2 NY3d at 510).
In determining the existence of “good cause,” a trial court must consider “whether present counsel is reasonably likely to afford a defendant effective assistance and whether the defendant has unduly delayed in seeking new assignment” (Medina, *59344 NY2d at 208). This Court has observed that “a conflict of interest or other irreconcilable conflict with counsel” may be “good cause for a substitution” (People v Sides, 75 NY2d 822, 824 [1990] [the Court concluded that the trial court abused its discretion by failing to inquire into defendant’s request for the assignment of substitute counsel]). However, the Court has also noted that courts have upheld refusal to assign substitute counsel where “tensions between client and counsel on the eve of trial were the precipitate of differences over strategy” or “where a defendant was guilty of delaying tactics” (Medina, 44 NY2d at 208 [citations omitted]).
Here, defendant failed to demonstrate that good cause for the substitution of assigned counsel existed. Supreme Court conducted an inquiry into defendant’s request for new assigned counsel. The inquiry revealed that defendant did not approve of the representation counsel sought to provide him despite counsel detailing that he had considered defendant’s motions, had prepared for trial and had tried numerous observation sale cases, which have similar factual allegations and issues as defendant’s case. The court noted that counsel was competent and likely to provide effective representation; the case was ready for trial; and defendant provided “no reason” to substitute counsel for a second time. Against this factual setting, the trial court’s denial of defendant’s request for the substitution of assigned counsel was a proper exercise of discretion.
“Evidence of prior specific criminal, vicious or immoral conduct should be admitted if the nature of such conduct or the circumstances in which it occurred bear logically and reasonably on the issue of credibility” (People v Sandoval, 34 NY2d 371, 376 [1974]). A court may exclude the evidence entirely; “limit [the prosecution’s] inquiry to the mere fact that there has been a prior conviction; it may limit inquiry to the existence and nature of the prior conviction; or it may permit examination into the facts and circumstances underlying the prior conviction” (People v Hayes, 97 NY2d 203, 208 [2002]). This determination, however, remains within the discretion of the trial court (see id. at 207).
It is important to note that the concerns observed by the Sandoval Court remain relevant. The Court recognized that the “cross-examination with respect to crimes or conduct similar to that of which the defendant is presently charged may be highly prejudicial” (Sandoval, 34 NY2d at 377). It stated,
“in the prosecution of drug charges, interrogation *594as to prior narcotics convictions (unless proof thereof is independently admissible) may present a special risk of impermissible prejudice because of the widely accepted belief that persons previously convicted of narcotics offenses are likely to be habitual offenders . . .
“In weighing prejudice to the defendant’s right to a fair trial, an important consideration may be the effect on the validity of the fact-finding process if the defendant does not testify out of fear of the impact of the impeachment testimony for reasons other than its direct effect on his credibility—as where the defendant would be the only available source of material testimony in support of his defense” (id. at 377-378).
Nonetheless, the Hayes Court, in a domestic violence case, concluded it is error to apply a fixed rule that requires trial courts to limit cross-examination “to the mere existence of defendant’s prior convictions where prior crimes are similar to the pending charges” (97 NY2d at 208). Because this Court has been disinclined over the years to construct per se rules concerning the cross-examination of a defendant where prior convictions are similar to the pending charges, the discretion of the trial court regarding such determinations remains intact. We reiterate, however, that trial courts should take care in weighing “whether the prejudicial effect of impeachment testimony far outweighs the probative worth of the evidence on the issue of credibility” (Sandoval, 34 NY2d at 376).
Here, defendant, on trial for several drug charges, requested that the prosecutor’s cross-examination of him be limited to the mere fact that his prior convictions were unspecified felonies. The trial court, instead, limited the prosecutor’s potential inquiry to the name of the crime, county and date of conviction and also advised that it would instruct the jury that the prior convictions are not evidence of defendant’s guilt. Although the concerns of Sandoval still exist and may have been implicated in this case, the court weighed appropriate concerns and limited the scope of cross-examination. Thus, pursuant to Hayes, no abuse of discretion is apparent.
Accordingly, the order of the Appellate Division should be affirmed.
Defendant’s first attorney had been substituted and replaced with the present trial counsel.