opinion: Chief Justice Rehnquist
  delivered the opinion of the Court.
  The issue in this case is whether the District Court erred in declining petitioner’s waiver of his right to conflict-free counsel and by refusing to permit petitioner’s proposed substitution of attorneys.
  I
  Petitioner Mark Wheat, along with numerous codefend-ants, was charged with participating in a far-flung drug distribution conspiracy. Over a period of several years, many thousands of pounds of marijuana were transported from Mexico and other locations to southern California. Petitioner acted primarily as an intermediary in the distribution ring; he received and stored large shipments of marijuana at his home, then distributed the marijuana to customers in the region.
  Also charged in the conspiracy were Juvenal Gomez-Barajas and Javier Bravo, who were represented in their criminal proceedings by attorney Eugene Iredale. Gomez-Barajas was tried first and was acquitted on drug charges overlapping with those against petitioner. To avoid a second trial on other charges, however, Gomez-Barajas offered to plead guilty to tax evasion and illegal importation of merchandise. At the commencement of petitioner’s trial, the District Court had not accepted the plea; Gomez-Barajas was thus free to withdraw his guilty plea and proceed to trial.
  Bravo, evidently a lesser player in the conspiracy, decided to forgo trial and plead guilty to one count of transporting approximately 2,400 pounds of marijuana from Los Angeles to a residence controlled by Victor Vidal. At the conclusion of Bravo’s guilty plea proceedings on August 22, 1985, Ire-dale notified the District Court that he had been contacted by petitioner and had been asked to try petitioner’s case as well. In response, the Government registered substantial concern about the possibility of conflict in the representation. After entertaining some initial discussion of the substitution of counsel, the District Court instructed the parties to present more detailed arguments the following Monday, just one day. before the scheduled start of petitioner’s trial.
  At the Monday hearing, the Government objected to petitioner’s proposed substitution on the ground that Iredale’s representation of Gomez-Barajas and Bravo created a serious conflict of interest. The Government’s position was premised on two possible conflicts. First, the District Court had not yet accepted the plea and sentencing arrangement negotiated between Gomez-Barajas and the Government; in the event that arrangement were rejected by the court, Gomez-Barajas would be free to withdraw the plea and stand trial. He would then be faced with the prospect of representation by Iredale, who in the meantime would have acted as petitioner’s attorney. Petitioner, through his participation in the drug distribution scheme, was familiar with the sources and size of Gomez-Barajas’ income, and was thus likely to be called as a witness for the Government at any subsequent trial of Gomez-Barajas. This scenario would pose a conflict of interest for Iredale, who would be prevented from cross-examining petitioner and thereby from effectively representing Gomez-Barajas.
  Second, and of more immediate concern, Iredale’s representation of Bravo would directly affect his ability to 'act as counsel for petitioner. The Government believed that a portion of the marijuana delivered by Bravo to Vidal’s residence eventually was transferred to petitioner. In this regard, the Government contacted Iredale and asked that Bravo be made available as a witness to testify against petitioner, and agreed in exchange to modify its position at the time of Bravo’s sentencing. In the likely event that Bravo were called to testify, Iredale’s position in representing both men would become untenable, for ethical proscriptions would forbid him to cross-examine Bravo in any meaningful way. By failing to do so, he would also fail to provide petitioner with effective assistance of counsel. Thus, because of Ire-dale’s prior representation of Gomez-Barajas and Bravo and the potential for serious conflict of interest, the Government urged the District Court to reject the substitution of attorneys.
  In response, petitioner emphasized his right to have counsel of his own choosing and the willingness of Gomez-Barajas, Bravo, and petitioner to waive the right to conflict-free counsel. Petitioner argued that the circumstances posited by the Government that would create a conflict for Iredale were highly speculative and bore no connection to the true relationship between the co-conspirators. If called to testify, Bravo would simply say that he did not know petitioner and had no dealings with him; no attempt by Iredale to impeach Bravo would be necessary. Further, in the unlikely event that Gomez-Barajas went to trial on the charges of tax evasion and illegal importation, petitioner’s lack of involvement in those alleged crimes made his appearance as a witness highly improbable. Finally, and most importantly, all three defendants agreed to allow Iredale to represent petitioner and to waive any future claims of conflict of interest. In petitioner’s view, the Government was manufacturing implausible conflicts in an attempt to disqualify Iredale, who had already proved extremely effective in representing Gomez-Barajas and Bravo.
  After hearing argument from each side, the District Court noted that it was unfortunate that petitioner had not suggested the substitution sooner, rather than two court days before the commencement of trial. The court then ruled:
  “[Bjased upon the representation of the Government in [its] memorandum that the Court really has no choice at this point other than to find that an irreconcilable conflict of interest exists. I don’t think it can be waived, and accordingly, Mr. Wheat’s request to substitute Mr. Ire-dale in as attorney of record is denied.” App. 100-101.
  Petitioner proceeded to trial with his original counsel and was convicted of conspiracy to possess more than 1,000 pounds of marijuana with intent to distribute, in violation of 21 U. S. C. §846, and five counts of possessing marijuana with intent to distribute, in violation of § 841(a)(1).
  The Court of Appeals for the Ninth Circuit affirmed petitioner’s convictions, 813 F. 2d 1399 (1987), finding that, within the limits prescribed by the Sixth Amendment, the District Court has considerable discretion in allowing substitution of counsel. The Court of Appeals found that the District Court had correctly balanced two Sixth Amendment rights: (1) the qualified right to be represented by counsel of one’s choice, and (2) the right to a defense conducted by an attorney who is free of conflicts of interest. Denial of either of these rights threatened the District Court with an appeal assigning the ruling as reversible error, and the Court of Appeals concluded that the District Court did not abuse its discretion in declining to allow the substitution or addition of Iredale as trial counsel for petitioner.
  Because the Courts of Appeals have expressed substantial disagreement about when a district court may override a defendant’s waiver of his attorney’s conflict of interest, we granted certiorari, 484 U. S. 814 (1987).
  HH HH
  The Sixth Amendment to the Constitution guarantees that “[i]n all criminal prosecutions, the accused shall enjoy the right... to have the Assistance of Counsel for his defence;” In United States v. Morrison, 449 U. S. 361, 364 (1981), we observed that this right was designed to assure fairness in the adversary criminal process. Realizing that an unaided layman may have little skill in arguing the law or in coping with an intricate procedural system, Powell v. Alabama, 287 U. S. 45, 69 (1932); United States v. Ash, 413 U. S. 300, 307 (1973), we have held that the Sixth Amendment secures the right to the assistance of counsel, by appointment if necessary, in a trial for any serious crime. Gideon v. Wainwright, 372 U. S. 335 (1963). We have further recognized that the purpose of providing assistance of counsel “is simply to ensure that criminal defendants receive a fair trial,” Strickland v. Washington, 466 U. S. 668, 689 (1984), and that in evaluating Sixth Amendment claims, “the appropriate inquiry focuses on the adversarial process, not on the accused’s relationship with his lawyer as such.” United States v. Cronic, 466 U. S. 648, 657, n. 21 (1984). Thus, while the right to select and be represented by one’s preferred attorney is comprehended by the Sixth Amendment, the essential aim of the Amendment is to guarantee an effective advocate for each criminal defendant rather than to ensure that a defendant will inexorably be represented by the lawyer whom he prefers. See Morris v. Slappy, 461 U. S. 1, 13-14 (1983); Jones v. Barnes, 463 U. S. 745 (1983).
  The Sixth Amendment right to choose one’s own counsel is circumscribed in several important respects. Regardless of his persuasive powers, an advocate who is not a member of the bar may not represent clients (other than himself) in court. Similarly, a defendant may not insist on representation by an attorney he cannot afford or who for other reasons declines to represent the defendant. Nor may a defendant insist on the counsel of an attorney who has a previous or ongoing relationship with an opposing party, even when the opposing party is the Government. The question raised in this case is the extent to which a criminal defendant’s right under the Sixth Amendment to his chosen attorney is qúalified by the fact that the attorney has represented other defendants charged in the same criminal conspiracy.
  In previous cases, we have recognized that multiple representation of criminal defendants engenders special dangers of which a court must be aware. While “permitting a single at-tomey to represent codefendants ... is not per se violative of constitutional guarantees of effective assistance of counsel,” Holloway v. Arkansas, 435 U. S. 475, 482 (1978), a court confronted with and alerted to possible conflicts of interest must take adequate steps to ascertain whether the conflicts warrant separate counsel. See also Cuyler v. Sullivan, 446 U. S. 335 (1980). As we said in Holloway:
  “Joint representation of conflicting interests is suspect because of what it tends to prevent the attorney from doing. . . . [A] conflict may . . . prevent an attorney from challenging the admission of evidence prejudicial to one client but perhaps favorable to another, or from arguing at the sentencing hearing the relative involvement and culpability of his clients in order to minimize the culpability of one by emphasizing that of another.” 435 U. S., at 489-490.
  Petitioner insists that the provision of waivers by all affected defendants cures any problems created by the multiple representation. But no such flat rule can be deduced from the Sixth Amendment presumption in favor of counsel of choice. Federal courts have an independent interest in ensuring that criminal trials are conducted within the ethical standards of the profession and that legal proceedings appear fair to all who observe them. Both the American Bar Association’s Model Code of Professional Responsibility and its Model Rules of Professional Conduct, as well as the rules of the California Bar Association (which governed the attorneys in this case), impose limitations on multiple representation of clients. See ABA Model Code of Professional Responsibility DR5-105(C) (1980); ABA Model Rules of Professional Conduct, Rule 1.7 (1984); Rules of Professional Conduct of the State Bar of California, Rules 5 and 7, Cal. Bus. & Prof. Code Ann. § 6076 (West 1974). Not only the interest of a criminal defendant but the institutional interest in the rendition of just verdicts in criminal cases may be jeopardized by unregulated multiple representation.
  For this reason, the Federal Rules of Criminal Procedure direct trial judges to investigate specially cases involving joint representation. In pertinent part, Rule 44(c) provides:
  “[T]he court shall promptly inquire with respect to such joint representation and shall personally advise each defendant of his right to the effective assistance of counsel, including separate representation. Unless it appears that there is good cause to believe no conflict of interest is likely to arise, the court shall take such measures as may be appropriate to protect each defendant’s right to counsel.”
  Although Rule 44(c) does not specify what particular measures may be taken by a district court, one option suggested by the Notes of the Advisory Committee is an order by the court that the defendants be separately represented in subsequent proceedings in the case. 18 U. S. C. App., p. 650. .This suggestion comports with our instructions in Holloway and in Glasser v. United States, 315 U. S. 60 (1942), that the trial courts, when alerted by objection from one of the parties, have an independent duty to ensure that criminal defendants receive a trial that is fair and does not contravene the Sixth Amendment.
  To be sure, this need to investigate potential conflicts arises in part from the legitimate wish of district courts that their judgments remain intact on appeal. As the Court of Appeals accurately pointed out, trial courts confronted with multiple representations face the prospect of being “whipsawed” by assertions of error no matter which way they rule. If a district court agrees to the multiple representation, and the advocacy of counsel is thereafter impaired as a result, the defendant may well claim that he did not receive effective assistance. See, e. g., Burger v. Kemp, 483 U. S. 776 (1987). On the other hand, a district court’s refusal to accede to the multiple representation may result in a challenge such as petitioner’s in this case. Nor does a waiver by the defendant necessarily solve the problem, for we note, without passing judgment on, the apparent willingness of Courts of Appeals to entertain ineffective-assistance claims from defendants who have specifically waived the right to conflict-free counsel. See, e. g., United States ex rel. Tonaldi v. Elrod, 716 F. 2d 431, 436-437 (CA7 1983); United States v. Vowteras, 500 F. 2d 1210, 1211 (CA2), cert. denied, 419 U. S. 1069 (1974); see also Glasser, supra, at 70 (“To preserve the protection of the Bill of Rights for hard-pressed defendants, we indulge every reasonable presumption against the waiver of fundamental rights”).
  Thus, where a court justifiably finds an actual conflict of interest, there can be no doubt that it may decline a proffer of waiver, and insist that defendants be separately represented. As the Court of Appeals for the Third Circuit stated in United States v. Dolan, 570 F. 2d 1177, 1184 (1978):
  “[W]hen a trial court finds an actual conflict of interest which impairs the ability of a criminal defendant’s chosen counsel to conform with the ABA Code of Professional Responsibility, the court should not be required to tolerate an inadequate representation of a defendant. Such representation not only constitutes a breach of professional ethics and invites disrespect for the integrity of the court, but it is also detrimental to the independent interest of the trial judge to be free from future attacks over the adequacy of the waiver or the fairness of the proceedings in his own court and the subtle problems implicating the defendant’s comprehension of the waiver.”
  Unfortunately for all concerned, a district court must pass on the issue whether or not to allow a waiver of a conflict of interest by a criminal defendant not with the wisdom of hindsight after the trial has taken place, but in the murkier pretrial context when relationships between parties are seen through a glass, darkly. The likelihood and dimensions of nascent conflicts of interest are notoriously hard to predict, even for those thoroughly familiar with criminal trials. It is a rare attorney who will be fortunate enough to learn the entire truth from his own client, much less be fully apprised before trial of what each of the Government’s witnesses will say on the stand. A few bits of unforeseen testimony or a single previously unknown or unnoticed document may significantly shift the relationship between multiple defendants. These imponderables are difficult enough for a lawyer to assess, and even more difficult to convey by way of explanation to a criminal defendant untutored in the niceties of legal ethics. Nor is it amiss to observe that the willingness of an attorney to obtain such waivers from his clients may bear an inverse relation to the care with which he conveys all the necessary information to them.
  For these reasons we think the district court must be allowed substantial latitude in refusing waivers of conflicts of interest not only in those rare cases where an actual conflict may be demonstrated before trial, but in the more common cases where a potential for conflict exists which may or may not burgeon into an actual conflict as the trial progresses. In the circumstances of this case, with the motion for substitution of counsel made so close to the time of trial, the District Court relied on instinct and judgment based on experience in making its decision. We do not think it can be said that the court exceeded the broad latitude which must be accorded it in making this decision. Petitioner of course rightly points out that the Government may seek to “manufacture” a conflict in order to prevent a defendant from having a particularly able defense counsel at his side; but trial courts are undoubtedly aware of this possibility, and must take it into consideration along with all of the other factors which inform this sort of a decision.
  Here the District Court was confronted not simply with an attorney who wished to represent two coequal defendants in a straightforward criminal prosecution; rather, Iredale proposed to defend three conspirators of varying stature in a complex drug distribution scheme. The Government intended to call Bravo as a witness for the prosecution at petitioner’s trial. The Government might readily have tied certain deliveries of marijuana by Bravo to petitioner, necessitating vigorous cross-examination of Bravo by petitioner’s counsel. Iredale, because of his prior representation of Bravo, would have been unable ethically to provide that cross-examination.
  Iredale had also represented Gomez-Barajas, one of the alleged kingpins of the distribution ring, and had succeeded in obtaining a verdict of acquittal for him. Gomez-Barajas had agreed with the Government to plead guilty to other charges, but the District Court had not yet accepted the plea arrangement. If the agreement were rejected, petitioner’s probable testimony at the resulting trial of Gomez-Barajas would create an ethical dilemma for Iredale from which one or the other of his clients would likely suffer.
  Viewing the situation as it did before trial, we hold that the District Court’s refusal to permit the substitution of counsel in this case was within its discretion and did not violate petitioner’s Sixth Amendment rights. Other district courts might have reached differing or opposite conclusions with equal justification, but that does not mean that one conclusion was “right” and the other “wrong.” The District Court must recognize a presumption in favor of petitioner’s counsel of choice, but that presumption may be overcome not only by a demonstration of actual conflict but by a showing of a serious potential for conflict. The evaluation of the facts and circumstances of each case under this standard must be left primarily to the informed judgment of the trial court.
  The judgment of the Court of Appeals is accordingly
  Affirmed.
  The Court of Appeals also found that petitioner was not prejudiced by a conference the District Court held with counsel in petitioner’s absence, and that petitioner had no right to insist upon a plea bargain from the Government. Our grant of certiorari, however, was limited to the issue addressed in the text of this opinion, and we do not reach the other rulings made by the Court of Appeals.
  See, e. g., In re Paradyne Corp., 803 F. 2d 604, 611, n. 16 (CA11 1986) (the right of counsel “does not override the broader societal interests in the effective administration of justice ... or in the maintenance of ‘public confidence in the integrity of our legal system’”) (citation omitted); In re Grand Jury Subpoena Served Upon Doe, 781 F. 2d 238, 250-251 (CA2), cert. denied sub nom. Roe v. United States, 475 U. S. 1108 (1986) (“[C]ourts have the power and duty to disqualify counsel where the public interest in maintaining the integrity of the judicial system outweighs the accused’s constitutional right”); United States v. Reese, 699 F. 2d 803, 805 (CA6 1983) (a trial court should override a defendant’s knowing waiver only in “compelling circumstances”); United States v. Flanagan, 679 F. 2d 1072, 1076 (CA3 1982) (a trial court may refuse a waiver'when an actual conflict is “very likely”), rev’d on other grounds, 465 U. S. 259 (1984).
  Our holding in Faretta v. California, 422 U. S. 806 (1975), that a criminal defendant has a Sixth Amendment right to represent himself if he voluntarily elects to do so, does not encompass the right to choose any advocate if the defendant wishes to be represented by counsel.
  Bravo was in fact called as a witness at petitioner’s trial. See Tr. 728 et seq. His testimony was elicited to demonstrate the transportation of drugs that the prosecution hoped to link to petitioner.
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