In criminal cases, a lawyer is typically in jeopardy of disqualification in the following four ethical dilemmas:
(1) when the lawyer represents two or more codefendants (a concurrent client conflict of interest);
(2) when the lawyer represents a prosecution witness or has previously represented a prosecution witness in the same or a related matter (a concurrent or former client conflict of interest);
(3) when the lawyer has previously represented the government in the matter or has otherwise obtained helpful confidential information while working for the government (a former client conflict of interest); and
(4) when the lawyer will be a necessary witness in the trial (a lawyer-as-witness role conflict).
These are the most common situations, although disqualification issues arise in many other situations. For example, the lawyer might also face disqualification: when the lawyer is implicated in criminal or professional misconduct in the matter; when the lawyer’s financial interests strongly conflict with the defendant’s interests; or when the lawyer has entered into a joint defense agreement (JDA) with another defendant, who then turns state’s evidence and against whom the lawyer may not use the information learned through the JDA to cross-examine her.
The following Charts (click on the image below) show the bases for all disqualification motions in federal criminal cases over roughly the last decade:
The Charts also suggest the grave disparity between the relatively high rate at which criminal defense counsel are disqualified (compared to civil attorneys) and the low rate at which federal prosecutors are disqualified (which is virtually zero). State prosecutors, though, are disqualified at a generally higher rate than federal prosecutors.
 See, e.g., Wheat v. United States, 486 U.S. 153 (1988) (affirming the denial of a motion to substitute counsel because counsel had represented two other defendants charged in the same conspiracy); see generally Holloway v. Arkansas, 435 U.S. 475, 476-77 (1978) (observing that “[p]etitioners, codefendants at trial, made timely motions for appointment of separate counsel, based on the representations of their appointed counsel that, because of confidential information received from the codefendants, he was confronted with the risk of representing conflicting interests and could not, therefore, provide effective assistance for each client” and concluding that “petitioners were deprived of the effective assistance of counsel by the denial of those motions”).
 See, e.g., United States v. Alfonzo-Reyes, 592 F.3d 280 (1st Cir. 2010) (affirming disqualification of defendant’s attorney even though the attorney’s former client-turned-witness was willing to waive the conflict); United States v. Iorizzo, 786 F.2d 52, 57 (2d Cir. 1986); United States v. Moscony, 927 F.2d 742, 748 (3d Cir. 1991) (concluding that, because the lawyer had formerly represented clients during the government’s investigation, and because those former clients were now expected to be government witnesses during the trial, the district court correctly “determined that fairness, both to Moscony and to the witnesses, dictated the disqualification of” the lawyer’s firm in part because cross-examination of the former clients “if foregone (which Moscony did not offer to do) would have deprived Moscony of his Sixth Amendment right to effective assistance of counsel (which Moscony did not offer to waive), and if pursued would have violated ethical standards regarding privileged communications (which the witnesses would not ‘waive’ even if they could)”); Gary T. Lowenthal, Successive Representation by Criminal Lawyers, 93 Yale L.J. 1, 56 (1983) (“When the former client of defense counsel testifying for the government desires disqualification to preserve confidential information, the government’s interest in seeking disqualification seems strongest.”); see generally Standards for Criminal Justice: Defense Function Standard 4-3.5(d) (1993) (“Defense counsel who has formerly represented a defendant should not thereafter use information related to the former representation to the disadvantage of the former client unless the information has become generally known or the ethical obligation of confidentiality otherwise does not apply.”). To avoid disqualification, courts can consider whether the witness will waive confidentiality and privilege, whether the testimony could be admitted through stipulation, and on “rare occasions,” whether to exclude the testimony to protect the defendant’s right to choice of counsel. See, e.g., United States v. Gearhart, 576 F.3d 459, 464-65 (7th Cir. 2009) (discussing other remedies and noting that “a district court may ‘on rare occasions’ exclude evidence to resolve a conflict of interest when ‘the probative value of the evidence is weighed against the negative consequences of admitting the evidence.’” (quoting United States v. Messino, 181 F.3d 826, 829-30 (7th Cir.1999))).
 See, e.g., United States v. Smith, 995 F.2d 662, 676 (7th Cir. 1993) (citing Wheat v. United States, 486 U.S. 153, 158–59 (1988)) (“We believe these facts were sufficient to allow [the district court] to conclude that Mr. Norris had substantial involvement with the investigation and thus presume that Mr. Norris received confidential information. See La Salle National Bank v. County of Lake, 703 F.2d 252, 255–56 (7th Cir.1983) (once substantial relationship established, court may presume confidential information was received). . . . It follows that the presumption in favor of permitting Marren to choose Mr. Norris was overcome by concerns for the integrity of the judicial process and that Marren’s Sixth Amendment right to counsel was not violated.”); Gary T. Lowenthal, Successive Representation by Criminal Lawyers, 93 Yale L.J. 1, 56 (1983) (noting the government’s strong interest in disqualification when the lawyer had formerly represented the government in related proceedings); see generally Standards for Criminal Justice: Defense Function Standard 4-3.5(h) (1993) (“Defense counsel who formerly participated personally and substantially in the prosecution of a defendant should not thereafter represent any person in the same or a substantially related matter. Defense counsel who was formerly a prosecutor should not use confidential information about a person acquired when defense counsel was a prosecutor in the representation of a client whose interests are adverse to that person in a matter.”).
 See, e.g., United States v. Locascio, 6 F.3d 924, 933 (2d Cir. 1993) (concluding that the district court properly disqualified the defense counsel because counsel “would function in his representational capacity as an unsworn witness for [the defendant]. An attorney acts as an unsworn witness when his relationship to his client results in his having first-hand knowledge of the events presented at trial. If the attorney is in a position to be a witness, ethical codes may require him to withdraw his representation.”); see generally Model Rules of Prof’l Conduct R. 3.7 (“A lawyer shall not act as advocate at a trial in which the lawyer is likely to be a necessary witness,” absent several exceptions.). To avoid unnecessary disqualification, the trial court must first determine that defense counsel will be a necessary witness at trial. See, e.g., State v. Van Dyck, 827 A.2d 192, 195 (N.H. 2003) (“We admonish trial courts to review motions to disqualify defense counsel in criminal cases cautiously to minimize the potential for abuse of the advocate-witness rule and the risk that a criminal defendant will be deprived unnecessarily of his chosen counsel.”); cf. Stacy Caplow, The Reluctant Witness for the Prosecution: Grand Jury Subpoenas to Defense Counsel, 51 Brook. L. Rev. 769, 788 (1985) (noting that the government can be “required to make a preliminary showing of reasonable need in addition to relevance when it subpoenas an attorney whose testimony before a grand jury investigating his or her client would result in the attorney’s disqualification”); Michael F. Orman, A Critical Appraisal of the Justice Department Guidelines for Grand Jury Subpoenas Issued to Defense Attorneys, 1986 Duke L.J. 145, 170 (“[A]n unethical prosecutor’s attempt to effect an attorney’s disqualification via a grand jury subpoena will fail unless the court determines that a showing of need for the attorney’s testimony at trial has been made which is sufficiently compelling to override the defendant’s qualified sixth amendment right.”).
 These four common categories are not mutually exclusive. For example, the lawyer may have previously represented a government witness, and for that reason, cannot effectively cross-examine that witness because the lawyer owes the witness a continuing duty of confidentiality. If the witness waives confidentiality, however, then the lawyer might need to consider testifying for the defendant. See, e.g., Bruce Green, Her Brother’s Keeper: The Prosecutor’s Responsibility When Defense Counsel Has a Potential Conflict of Interest, 16 Am. J. Crim. L. 323, 332-333 (1989) (discussing United States v. Mitchell, 572 F. Supp. 709 (N.D. Cal. 1983), aff’d 736 F.2d 1299 (9th Cir. 1984)).
 See, e.g., 3 Wayne R. LaFave et al., Crim. Proc. § 11.9(a) (3d ed. 2013) (citing Mannhalt v. Reed, 847 F.2d 576, 583-84 (9th Cir. 1988)) (“[T]he paradigm case is that in which the lawyer representing the defendant fears opening himself up to criminal prosecution because he is under investigation for an offense relating to the same events.”); cf. United States v. Ziegenhagen, 890 F.2d 937, 940-41 (7th Cir. 1989) (declaring an “actual conflict of interest” because a defense attorney had been put in a position in which his duty to his current client, a criminal defendant, might require the attorney to challenge a conviction he had previously obtained against the client while serving as a prosecutor); Mathis v. Hood, 937 F.2d 790, 795-96 (2d Cir. 1991) (affirming “the judgment of the district court based on its conclusion that Mathis’s attorney had an actual conflict of interest sufficient to undermine its confidence in the outcome of the appeal, a conflict that established a per se violation of Mathis’s right to effective assistance of counsel” because the attorney’s misconduct was in issue).
 See generally United States v. Schwarz, 283 F.3d 76, 81 (2d Cir. 2002) (“hold[ing] that Schwarz’s convictions for the civil rights violations must be vacated and remanded for a new trial because his attorney’s unwaivable conflict of interest denied him effective assistance of counsel” given that the attorney’s firm had a multi-million dollar retainer agreement with a police union that had adverse interests to the defendant); Winkler v. Keane, 7 F.3d 304, 307-08 (2d Cir. 1993) (“Winkler argues that the contingency fee created an actual conflict of interest for trial counsel because Winkler’s interests in effective representation were pitted against trial counsel’s monetary interest. We agree. The contingency fee agreement in this case provided trial counsel with an extra $25,000 only if Winkler was acquitted or otherwise not found guilty. Thus, trial counsel had a disincentive to seek a plea agreement, or to put forth mitigating defenses that would result in conviction of a lesser included offense. Plainly the contingency fee agreement created an actual conflict of interest.”); 3 Wayne R. LaFave et al., Crim. Proc. § 11.9(d) (3d ed. 2013) (noting that the attorney’s interest in the case’s media rights or marketability might violate the defendant’s rights and citing Buenoano v. Singletary, 963 F.2d 1433 (11th Cir. 1992); United States v. Hearst, 638 F.2d 1190 (9th Cir. 1980); Dumond v. State, 743 S.W.2d 779 (Ark. 1988)); cf. Wood v. Georgia, 450 U.S. 261, 272 (1981) (reversing in part because the defendant-employee’s lawyer may have been “influenced in his basic strategic decisions by the interests of the employer who hired him”).
 See, e.g., United States v. Henke, 222 F.3d 633, 636 (9th Cir. 2000) (agreeing with “defendants’ principal claim . . . that they are entitled to a new trial because their attorneys worked under an actual conflict of interest that prohibited them from cross-examining one of the government’s key witnesses”); see generally Matthew D. Forsgren, The Outer Edge of the Envelope: Disqualification of White Collar Criminal Defense Attorneys Under the Joint Defense Doctrine, 78 Minn. L. Rev. 1219, 1244 (1994) (“Even when prevailing ethical rules support disqualification, however, the Sixth Amendment further requires courts to balance the defendant’s right to counsel of choice against the interests of the government witness. Although the Supreme Court has seemingly reduced the right to counsel of choice to a weak presumption, lower courts still recognize that adversarial fairness in complex criminal cases largely depends on access to counsel of choice.”). Disqualification might be avoided if the JDA explicitly waived that remedy. See, e.g., In re Shared Memory Graphics LLC, 659 F.3d 1336, 1342 (Fed. Cir. 2011) (upholding advance waiver).
 To be counted, the cases had to concern and adjudicate motions to disqualify. Thus, non-dispositive or merely analogous cases were not counted. See, e.g., Lambright v. Ryan, 698 F.3d 808, 826 (9th Cir. 2012) (refraining to review as moot the district court’s disqualification analysis); United States v. Scruggs, 691 F.3d 660, 669 (5th Cir. 2012) (addressing the defendant’s later ineffective assistance of counsel claim based on an alleged conflict of interest). Habeas cases were also not counted because they, at least technically, were civil cases. Because only federal decisions were counted, moreover, we must be careful about relying too heavily on the results; state courts rendered many decisions during this timeframe, and those decisions are not reflected in the results.
[Original Source: Keith Swisher, Disqualifying Defense Counsel: The Curse of the Sixth Amendment, 4 St. Mary’s J. Legal Malpractice & Ethics 374 (2014).]