Erwine v. Westbrook

FOR PUBLICATION UNITED STATES COURT OF APPEALS FOR THE NINTH CIRCUIT MICHAEL ERWINE, No. 25-3136 D.C. No. Plaintiff - Appellant, 3:24-cv-00045- MMD-CSD v. ZACHARY WESTBROOK; JOHN LEONARD; MICHEL HALL; OPINION GENE M. BURKE, Defendants - Appellees, and UNITED STATES OF AMERICA, COUNTY OF CHURCHILL, BENJAMIN TROTTER, Defendants. Appeal from the United States District Court for the District of Nevada Miranda M. Du, District Judge, Presiding Argued and Submitted March 11, 2026 Las Vegas, Nevada 2 ERWINE V. WESTBROOK Filed September 11, 2026 Before: Mark J. Bennett and Gabriel P. Sanchez, Circuit Judges, and John W. Holcomb, District Judge.* Opinion by Judge Bennett SUMMARY** Tribal Immunity / Required Party The panel reversed the district court’s dismissal of an action brought by Michael Erwine, a former police officer for the Washoe Tribe of Nevada and California, alleging federal civil rights claims and a Nevada tort claim against several of his superior officers and the Tribe’s general counsel after Erwine was terminated from his position. The district court concluded that the individual officers were entitled to absolute personal immunity, and, alternatively, that the Tribe was a required party under Fed. R. Civ. P. 19 which could not be joined in the action on account of its sovereign immunity. The panel held that tribal sovereign immunity did not bar this suit. Erwine does not seek money damages from the tribal treasury, but rather from the tribal defendants * The Honorable John W. Holcomb, United States District Judge for the Central District of California, sitting by designation. ** This summary constitutes no part of the opinion of the court. It has been prepared by court staff for the convenience of the reader.  ERWINE V. WESTBROOK 3 personally. Because any judgment will not operate against the Tribe, the Tribe was not the real party in interest, and sovereign immunity did not shield the Tribal Officers from Erwine’s claims. The panel further held that the individual officers did not enjoy absolute immunity. A functional approach governs when a tribal employee raises absolute immunity as a defense in an individual-capacity action arising under federal law. The Tribal Officers failed to meet their burden of showing absolute immunity was justified for the function in question, and the district court erred in dismissing Erwine’s federal claims on absolute immunity grounds. Turning to Erwine’s Nevada tort claim for intentional interference with contractual relations against the Tribe’s general counsel, the panel concluded that a tribe’s conferral of immunity did not, by its own force, entitle an officer to absolute immunity in an individual-capacity suit arising under Nevada state law. The panel also held that the Tribe was not a required party under Rule 19. Rule 19 sets forth a three-step inquiry, and the parties only dispute the first step of the inquiry: whether the Tribe is a required party. The panel held that because the Tribe did not have a legally protected interest in the outcome of the litigation that might be impaired in its absence, the district court erred in determining that the Tribe was a required party under Rule 19. Having determined that the Tribe was not a required party, the panel did not proceed to the remaining steps of the Rule 19 inquiry. The panel left the Tribal Officers’ qualified immunity defenses for the district court to consider in the first instance on remand. 4 ERWINE V. WESTBROOK COUNSEL Luke A. Busby (argued), Luke Andrew Busby Ltd., Reno, Nevada, for Plaintiff-Appellant. Leonard R. Powell (argued) and Morgan E. Saunders, Native American Rights Fund, Washington, D.C.; Sydney A. Tarzwell, Native American Rights Fund, Anchorage, Alaska; Katherine F. Parks, Thorndal Armstrong PC, Reno, Nevada; Defendants-Appellees. Joseph D. Nady, General Counsel, Washoe Tribe of Nevada and California, Gardnerville, Nevada, for Amicus Curiae The Washoe Tribe of Nevada and California. OPINION BENNETT, Circuit Judge: Michael Erwine served as a police officer for the Washoe Tribe of Nevada and California (the “Tribe”). After the Tribe terminated Erwine from that position, he sued several of his superior officers and the Tribe’s general counsel, bringing federal civil rights claims and a Nevada tort claim. Erwine did not sue the Tribe. The district court granted the defendants’ motion to dismiss, concluding that the individual officers are entitled to absolute personal immunity and, alternatively, that the Tribe is a required party under Federal Rule of Civil Procedure 19 which cannot be joined in the action on account of its sovereign immunity. The district court declined to address the officers’ contentions that tribal  ERWINE V. WESTBROOK 5 sovereign immunity and qualified immunity also compelled dismissal. All four grounds for affirmance are before us. We reject three and leave one for the district court to consider. We conclude that tribal sovereign immunity does not bar this suit, that the individual officers do not enjoy absolute immunity, and that the Tribe is not a required party under Rule 19. We leave the qualified immunity defenses for the district court to consider in the first instance. Thus, we reverse and remand. I Because this appeal arises from a motion to dismiss, we recite the facts as set forth in the plaintiff’s complaint. See Nguyen v. Endologix, Inc., 962 F.3d 405, 408 (9th Cir. 2020). The Tribe is a federally recognized Indian tribe. See Indian Entities Recognized by and Eligible to Receive Services from the United States Bureau of Indian Affairs, 89 Fed. Reg. 99899, 99902 (Dec. 11, 2024). Under the Indian Self-Determination and Education Assistance Act of 1975, 25 U.S.C. § 5301 et seq., the Tribe receives funding for its police department from the federal government via a self-determination contract with the United States. Through its Law and Order Code, the Tribe extends immunity to its officers and employees against “claim[s]” seeking “to recover damages from . . . [them], while engaged in work assigned or controlled by the Tribe.” Washoe Tribe of Nevada and California Law & Order Code §§ 33-20(2), 33-30-010 (2014). Erwine began working as a police officer for the Tribe on October 18, 2019. The Tribe terminated his employment on March 4, 2022. That day, Erwine met with Chief of Police Zachary Westbrook, Deputy Chief of Police John 6 ERWINE V. WESTBROOK Leonard, Sergeant Michel Hall, and the Tribe’s general counsel Gene Burke. Westbrook informed Erwine of the decision and said that the Tribal Chairman had signed off on it. Erwine then filed an action in federal court, suing, as relevant here, Chief Westbrook, Deputy Chief Leonard, Sergeant Hall, and Burke (the “Tribal Officers”). Erwine seeks money damages from those defendants in their individual capacities, bringing claims for race discrimination under 42 U.S.C. § 1981, conspiracy to interfere with civil rights under 42 U.S.C. § 1985(2), and conspiracy to interfere with civil rights under 42 U.S.C. § 1985(3). Erwine alleges that the Tribal Officers treated him, a white employee, less favorably than similarly situated Native American employees, subjected him to a racially hostile work environment, conspired to deter him from testifying in court in connection with a lawsuit against his former employer, and conspired to deprive him of his due process rights in his employment and reputation. Erwine also brings a Bivens claim for discrimination under Davis v. Passman, 442 U.S. 228 (1979), against Chief Westbrook, Deputy Chief Leonard, and Sergeant Hall (but not against Burke). Finally, Erwine brings a Nevada tort claim for intentional interference with contractual relations against Burke. Erwine did not sue the Tribe. The Tribal Officers moved to dismiss, asserting absolute immunity, qualified immunity, tribal sovereign immunity, and failure to join the Tribe as a Rule 19 required party. The district court dismissed the claims against the Tribal Officers. It concluded that absolute immunity bars Erwine’s claims and, alternatively, that the Tribe is a required party under Rule 19 but cannot be joined because of tribal  ERWINE V. WESTBROOK 7 sovereign immunity. The district court did not address the Tribal Officers’ arguments as to sovereign immunity or qualified immunity. As to absolute immunity, the district court reasoned that the Tribe, through its Code, has “immunize[d] tribal officers and employees from demands to recover damages arising from work they do for the Tribe.” Because the Tribal Officers’ alleged misconduct “all fall[s] within the scope of their official duties,” the district court determined that absolute immunity compelled dismissal. As to Rule 19, the district court found that the Tribe is a required party because the proceedings implicate the Tribe’s “sovereign interest in setting and enforcing its own employment policies.” In the district court’s view, evaluating Erwine’s claims would require a federal court to undertake a “detailed review of the Washoe Tribe’s policies as applied to the facts of Erwine’s termination,” which “would impinge on the Washoe Tribe’s ability to govern itself.” Based on its ruling that the Tribe cannot be joined because of tribal sovereign immunity, the district court exercised its discretion to dismiss the claims against the Tribal Officers. See Klamath Irrigation Dist. v. U.S. Bureau of Reclamation, 48 F.4th 934, 943 (9th Cir. 2022). The district court then granted, and the clerk entered, judgment for the Tribal Officers pursuant to Rule 54(b). Erwine now appeals. II Suits against tribal officials and employees can implicate two types of immunity defenses: sovereign immunity and personal immunity. The Tribal Officers contend that each shields them from Erwine’s claims. 8 ERWINE V. WESTBROOK A “Indian tribes,” the Supreme Court has explained, “exercise inherent sovereign authority over their members and territories.” Okla. Tax Comm’n v. Citizen Band Potawatomi Indian Tribe, 498 U.S. 505, 509 (1991). “[U]nless and ‘until Congress acts, the tribes retain’ their historic sovereign authority.” Michigan v. Bay Mills Indian Cmty., 572 U.S. 782, 788 (2014) (quoting United States v. Wheeler, 435 U.S. 313, 323 (1978), superseded by statute on other grounds as recognized in United States v. Lara, 541 U.S. 193, 207 (2004)). Among the retained aspects of tribal sovereignty is “the common-law immunity from suit traditionally enjoyed by sovereign powers.” Santa Clara Pueblo v. Martinez, 436 U.S. 49, 58 (1978). “Suits against Indian tribes are thus barred by sovereign immunity absent a clear waiver by the tribe or congressional abrogation.” Okla. Tax Comm’n, 498 U.S. at 509. “[W]hen a defendant timely and successfully invokes tribal sovereign immunity, we lack subject matter jurisdiction.” Acres Bonusing, Inc v. Marston, 17 F.4th 901, 908 (9th Cir. 2021). And “[b]ecause we may not issue a ‘judgment on the merits’ and assume our ‘substantive law- declaring power’ before first confirming we have jurisdiction, we address tribal sovereign immunity at the outset,” id. (quoting Sinochem Int’l Co. v. Malaysia Int’l Shipping Corp., 549 U.S. 422, 431, 433 (2007)), even though the district court declined to do so. B To evaluate an assertion of tribal sovereign immunity, we apply the framework clarified by the Supreme Court in Lewis v. Clarke, 581 U.S. 155 (2017). That case arose when a tribal employee, in the course and scope of his tribal  ERWINE V. WESTBROOK 9 employment, rear-ended another vehicle while driving casino patrons home from a tribal casino. See id. at 159–60. The owners of the other vehicle brought a negligence claim against the tribal employee in his individual capacity. See id. at 157, 160. Invoking tribal sovereign immunity, the employee moved to dismiss for lack of subject matter jurisdiction. See id. at 160. The Supreme Court held that tribal sovereign immunity did not bar the negligence claim. See id. at 167–68. “The protection offered by tribal sovereign immunity,” the Court explained, “is no broader than the protection offered by state or federal sovereign immunity.” Id. at 164. In those contexts, courts “look to whether the sovereign is the real party in interest to determine whether sovereign immunity bars the suit.” Id. at 161–62. To assess whether the sovereign is the real party in interest, a court must determine “whether the remedy sought is truly against the sovereign.” Id. at 162. And the answer to that question rests on “[t]he distinction between individual- and official- capacity suits.” Id. “In an official-capacity claim, the relief sought is only nominally against the official and in fact is against the official’s office and thus the sovereign itself. This is why, when officials sued in their official capacities leave office, their successors automatically assume their role in the litigation.” Id. (citations omitted). “Because the relief requested effectively runs against the sovereign, the sovereign is the real party in interest, and sovereign immunity may be an available defense.” Acres Bonusing, 17 F.4th at 909. But in suits against officials in their personal capacities, the plaintiff “seek[s] to impose individual liability upon a 10 ERWINE V. WESTBROOK government officer for actions taken under color of . . . law.” Lewis, 581 U.S. at 162 (quoting Hafer v. Melo, 502 U.S. 21, 25 (1991)). “‘[O]fficers sued in their personal capacity come to court as individuals,’ and the real party in interest is the individual, not the sovereign.” Id. at 162–63 (alteration in original) (quoting Hafer, 502 U.S. at 27). Thus, “sovereign immunity ‘does not erect a barrier against suits to impose individual and personal liability.’” Id. at 163 (quoting Hafer, 502 U.S. at 30–31). Against this backdrop, the Supreme Court concluded that “in a suit brought against a tribal employee in his individual capacity, the employee, not the tribe, is the real party in interest and the tribe’s sovereign immunity is not implicated.” Id. at 158. “That an employee was acting within the scope of his employment at the time the tort was committed,” the Court underscored, “is not, on its own, sufficient to bar a suit against that employee on the basis of tribal sovereign immunity.” Id. Applying those principles to the case before it—a negligence action arising from a tort committed by a tribal employee acting within the scope of his employment— Lewis observed that the suit sought to recover for the employee’s “personal actions.” Id. at 163. Because the plaintiff did not sue the employee in his official capacity and “the judgment w[ould] not operate against the [t]ribe,” the Supreme Court determined that the tribe was not the real party in interest. See id. at 163–64. Sovereign immunity thus did not bar the suit. See id. Our decision in Acres Bonusing followed Lewis. The plaintiffs sought damages against tribal employees, including a tribal court judge, his law clerks, and the clerk of the tribal court, in their individual capacities. See Acres  ERWINE V. WESTBROOK 11 Bonusing, 17 F.4th at 905. In asserting sovereign immunity, the tribal employees tried to distinguish Lewis by arguing that the Court’s holding extended only to “garden variety torts with no relationship to tribal governance and administration.” Id. at 911. The allegedly tortious conduct in Acres Bonusing, by contrast, occurred in tribal court. See id. Because “tribal courts are part of [a] [t]ribe’s inherently sovereign functions,” the tribal employees urged that “adjudicating th[e] dispute would require the court to interfere with the tribe’s internal governance.” Id. So, the tribal employees argued, the tribe was indeed the real party in interest, and the suit implicated its sovereign immunity. Id. We rejected that view. “[T]he tribal sovereign immunity analysis,” we explained, does not “turn on a freestanding assessment of whether the suit related to tribal governance in some way.” Id. “[N]either Lewis nor our prior cases evaluated the degree to which the suits could involve consideration of issues that relate to tribal governance or administration.” Id. at 912. Indeed, “[s]uch an analysis would likely prove difficult because any suit against a tribal employee for conduct in the course of her official duties almost inevitably has some valence to tribal governance.” Id. “And if that were the test, we would seemingly end up applying tribal sovereign immunity whenever a tribal employee was acting within the scope of her employment— which is precisely what the Supreme Court in Lewis said not to do.” Id. Instead, we clarified that “[t]he question is whether ‘any remedy will operate . . . against the sovereign.’” Id. at 911 (omission in original) (quoting Pistor v. Garcia, 791 F.3d 1104, 1113 (9th Cir. 2015)). Or, as the Supreme Court put it, “[t]he critical inquiry is who may be legally bound by the 12 ERWINE V. WESTBROOK court’s adverse judgment.” Lewis, 581 U.S. at 165. Thus, when a plaintiff’s “suit for damages against tribal employees and agents ‘will not require action by the sovereign or disturb the sovereign’s property,’ and any ‘judgment will not operate against the [t]ribe,’ tribal sovereign immunity does not apply.” Acres Bonusing, 17 F.4th at 913 (quoting Lewis, 581 U.S. at 163). Because the plaintiffs in Acres Bonusing sought money damages against the defendants in their individual capacities, any relief ordered would not have required the tribe “to do or pay anything.” Id. at 910. So we concluded that “any ‘judgment w[ould] not operate against the [t]ribe,’ [the tribe] [wa]s not the real party in interest, and tribal sovereign immunity d[id] not apply.” Id. (quoting Lewis, 581 U.S. at 163). The same outcome followed in Welsh v. Loudbear, 178 F.4th 484 (9th Cir. 2026). Plaintiffs there sued tribal employees in their individual capacities and “s[ought] damages resulting from alleged criminal acts carried out by individuals, not [the tribe].” Id. at 489. “After Lewis,” we explained, “the relevant inquiry when determining whether tribal officials enjoy sovereign immunity is ‘whether the remedy sought is truly against the sovereign.’” Id. (quoting Lewis, 581 U.S. at 162). Because the complaint sought “recovery only from the tribal [employees] and d[id] not attempt to impose liability on [the tribe],” only the individual employees could be “ordered to pay the judgment”—not the tribe itself. Id. Thus, we determined that the tribal employees were not entitled to invoke the tribe’s sovereign immunity. See id. at 489–90.  ERWINE V. WESTBROOK 13 C Applying the remedy-focused test expounded by Lewis, Acres Bonusing, and Welsh, we conclude that tribal sovereign immunity does not bar this suit. Like the plaintiffs in those cases, Erwine seeks “money damages not from the tribal treasury but from the tribal defendants personally.” See Acres Bonusing, 17 F.4th. at 912 (quoting Pistor, 791 F.3d at 1113). Because any “judgment will not operate against the Tribe,” Lewis, 581 U.S. at 163, the Tribe is not the real party in interest, and sovereign immunity does not shield the Tribal Officers from Erwine’s claims. The Tribal Officers resist this conclusion, arguing that the litigation will “interfere with [the] [T]ribe’s internal governance,” because Erwine “seeks to hold [the] Tribal [Officers] liable for tribal employment decisions central to the operation of the Tribe’s police department and the administration of its grievance process.” But our precedent forecloses the Tribal Officers’ contention. We do not evaluate the degree to which a suit relates to tribal governance. See Acres Bonusing, 17 F.4th at 911–13. It is instead “the ‘remedy sought’ [that] governs the tribal sovereign immunity analysis.” Id. at 912 (quoting Lewis, 581 U.S. at 162). And under this “remedy-focused analysis,” id. at 911 (quoting Maxwell v. County of San Diego, 708 F.3d 1075, 1088 (9th Cir. 2013)), the Tribal Officers are not entitled to tribal sovereign immunity. III Even when tribal sovereign immunity does not bar a suit, tribal officials sued in their individual capacities may still invoke “personal immunity defenses” such as absolute immunity or qualified immunity. See Lewis, 581 U.S. at 163; Acres Bonusing, 17 F.4th at 915. The district court 14 ERWINE V. WESTBROOK determined that absolute immunity bars each of Erwine’s claims against the Tribal Officers. We review de novo questions of personal immunity, see Acres Bonusing, 17 F.4th at 907, and we conclude that the Tribal Officers are not protected by absolute immunity. A “Absolute immunity is an extraordinary attribute. Those who act while clad in its armor cannot be held liable for damages under any circumstances, even if they violate clearly established federal rights, and even if they do so intentionally or maliciously.” Brooks v. Clark County, 828 F.3d 910, 915–16 (9th Cir. 2016). As a result, the Supreme Court has been “‘quite sparing’ in [its] recognition of absolute immunity, and ha[s] refused to extend it any ‘further than its justification would warrant.’” Burns v. Reed, 500 U.S. 478, 487 (1991) (first quoting Forrester v. White, 484 U.S. 219, 224 (1988); and then quoting Harlow v. Fitzgerald, 457 U.S. 800, 811 (1982)). Thus, “[t]he presumption is that qualified rather than absolute immunity is sufficient to protect government officials in the exercise of their duties.” Id. at 486–87. And “the official seeking absolute immunity bears the burden of showing that such immunity is justified.” Id. at 486. “Tribal officials, like federal and state officials, can invoke personal immunity defenses.” Acres Bonusing, 17 F.4th at 915. In Lewis, the Supreme Court “described the availability of personal immunity defenses in the context of discussing generally applicable principles of individual and official capacity suits.” Id. And the Court also explained that “[t]here is no reason to depart from these general rules in the context of tribal sovereign immunity.” Id. (alteration in original) (quoting Lewis, 581 U.S. at 163). “Those  ERWINE V. WESTBROOK 15 ‘general rules’ thus include[] . . . common law personal immunity defenses.” Id. “In determining whether particular actions of government officials fit within a common-law tradition of absolute immunity,” the Supreme Court has prescribed a “functional approach.” Buckley v. Fitzsimmons, 509 U.S. 259, 269 (1993) (quoting Burns, 500 U.S. at 486). “We consult the common law to identify those governmental functions that were historically viewed as so important and vulnerable to interference by means of litigation that some form of absolute immunity from civil liability was needed to ensure that they are performed ‘with independence and without fear of consequences.’” Rehberg v. Paulk, 566 U.S. 356, 363 (2012) (quoting Pierson v. Ray, 386 U.S. 547, 554 (1967)). The Court has identified several functions as protected by absolute immunity from civil liability, including “actions taken by legislators within the legitimate scope of legislative authority, actions taken by judges within the legitimate scope of judicial authority, actions taken by prosecutors in their role as advocates, and the giving of testimony by witnesses at trial.” Id. at 363 (citations omitted). In Acres Bonusing, we evaluated the absolute immunity defense raised by tribal officials under this functional approach. See 17 F.4th at 915–16. We determined that several officials—the tribal court judge, his law clerks, and the clerk of the tribal court—performed judicial or quasi-judicial functions. See id. So we affirmed the dismissal of those defendants based on absolute immunity. See id. at 916–17. 16 ERWINE V. WESTBROOK B The Tribal Officers contend that the functional approach does not apply here. Though they concede that federal and state officials enjoy absolute immunity only when their “special functions require a full exemption from liability,” they claim that “tribal immunities are broader than federal and state immunities in many areas.” One such area, the Tribal Officers contend, is that tribes may “bestow” absolute immunity on tribal officials for acts taken within areas of tribal control. The Tribal Officers’ argument relies mainly on Davis v. Littell, 398 F.2d 83 (9th Cir. 1968). In Davis, a former tribal employee brought a defamation suit against his former boss, the general counsel of the Navajo Tribe. See id. at 83–84. The plaintiff alleged that the general counsel had “reported to the Tribal Council his views as to the competence and integrity of [the plaintiff]” and that, because of those statements, the plaintiff “was discharged from office and suffered loss of reputation.” Id. at 84–85. The district court granted summary judgment for the general counsel, finding him immune from liability. See id. at 84. We affirmed. See id. at 86. Davis began by determining “[w]hether the Navajo Tribe enjoys sufficient independent status and control over its own laws and internal relationships to be able to accord absolute privilege to its officers within the areas of tribal control.” Id. at 84. Because “tribal sovereignty has been found a sufficient basis for extending to Indian tribes sovereign immunity from suit,” we concluded that the tribe could bestow immunity on its officers. Id. We then considered whether the Navajo Tribe had, in fact, bestowed immunity. See id. We found that it had.  ERWINE V. WESTBROOK 17 Though the Navajo Tribe’s Tribal Code did not expressly bestow immunity on tribal officers, the Code suggested that the immunity question should “be guided by federal or appropriate state law.” Id. (citing Navajo Tribal Code, tit. 7, ch. 3, § 34(C)). And both federal law and Arizona law, we determined, recognized absolute executive immunity for defamation. See id. at 84–85. From there, we evaluated whether the general counsel could claim absolute executive immunity. That question turned on “whether [the position] encompasses public duties, official in character.” Id. at 85. The functions of the general counsel included providing “advice with respect to the administration of the public affairs of the [t]ribe.” Id. And looking to the plaintiff’s complaint, the alleged defamation had “resulted from the manner in which [the general counsel] reported to the Tribal Council his views as to the competence and integrity of [the plaintiff], a subordinate employee.” Id. Those duties, we determined, “are precisely the duties which were regarded as requiring the protection of privilege”—“the elimination of the ‘constant dread of retaliation’ for injury committed in the course of duty and the allowance of ‘unflinching discharge of (official) duties’ free from the threat of suit and charge of malice.” Id. (quoting Gregoire v. Biddle, 177 F.2d 579, 581 (2d Cir. 1949)). We finally considered whether Arizona courts would honor this immunity “bestowed by a foreign sovereign in a suit brought by an Arizona citizen.” Id. Because “the state, in the public interest, ha[d] seen fit to formulate [the immunity]” so as to protect its own officers, we reasoned that it would be “inconsistent for [Arizona] to cherish the rule for itself while denying its benefits to a sovereign which does not possess the economic power to provide a just 18 ERWINE V. WESTBROOK alternative.” Id. at 84–85. On that basis, we predicted that “Arizona state courts would accord comity to an Indian tribe geographically located within the state boundaries.” Id. at 86. Absolute immunity thus barred the assistant’s claim against the general counsel. See id. at 83, 86. The Tribal Officers contend that Davis resolves this case. Their argument proceeds in several steps. At the first step, they draw parallels between Davis and this case. Like the assistant in Davis, Erwine is a terminated tribal employee seeking to sue his former supervisors. Like the Navajo Tribe, the Washoe Tribe is a sovereign that can bestow immunity upon its officials. And based on the allegations in the complaint, the Tribal Officers also analogize that Erwine, like the assistant, seeks to recover damages in connection with work assigned or controlled by the Tribe. That much is true. Erwine’s claims turn on allegations that the Tribal Officers supervised, reported on, and ultimately terminated him from the tribal police force. And Erwine alleges that the Tribal Officers acted as officers or employees of the Tribe “at the times relevant to [the] complaint.” Indeed, the Tribe’s amicus brief confirms that “the actions described [in the complaint] were taken in the performance of the [Tribal Officers’] official duties” and “fall within the scope of work assigned or controlled by the Tribe.” At the next step, the Tribal Officers stress one key difference between Davis and this case. Unlike the Navajo Tribal Code, the Washoe Tribe’s Code expressly bestows absolute immunity on its officers. Title 33 of the Washoe Tribe’s Law & Order Code provides that “[t]he sovereign immunity of the Tribe shall include but not be limited to any lawsuit, action, claim, controversy or process, in any state,  ERWINE V. WESTBROOK 19 federal, or Tribal court, forum, or tribunal, unless such immunity is clearly, explicitly and unequivocally waived.” Washoe Tribe of Nevada and California Law & Order Code § 33-30-010 (2014). And the Code defines “[c]laim” as “any written demand to recover damages from the Tribe or Tribal Entity, or an officer or employee of the Tribe or Tribal Entity, while engaged in work assigned or controlled by the Tribe or Tribal Entity.” Id. § 33-20(2). Thus, as the Tribal Officers see it, whether they can claim the immunity conferred by tribal law is readily resolved in their favor because Davis commands that result. The district court agreed. Applying Davis, it explained that “Title 33 of the Washoe Tribe’s Law and Order Code bestowed absolute immunity on [the Tribal Officers] for their alleged actions described in the [complaint]— disciplining and ultimately firing Erwine,” and these actions “fall[] within the scope of their official duties.” The district court thus held that absolute immunity bars Erwine’s claims. We disagree. C Davis’s conclusion that the tribal official enjoyed absolute immunity rested on our finding that Arizona courts would recognize the Navajo Tribe’s conferral of absolute immunity out of comity. The Tribal Officers would have us extend Davis. On their reading, Davis empowers a tribe to confer absolute immunity on its officials whenever they act within areas of tribal control—including to bar liability in suits arising under federal and state law, even when the law under which the cause of action arises would not recognize that immunity. We decline to extend Davis in this manner. Instead, we conclude that for an immunity conferred by a tribe on its 20 ERWINE V. WESTBROOK officials to apply, the specific immunity conferred by tribal law must be consistent with the law under which the cause of action arises. Thus, our analysis of Erwine’s federal civil rights claims is somewhat different than our analysis of his Nevada tort claim. But we reject the Tribal Officers’ assertion of absolute immunity as to both. 1 We begin with Erwine’s federal civil rights claims against the Tribal Officers. Recall that Erwine brings claims under 42 U.S.C. §§ 1981, 1985(2), and 1985(3) and brings a Bivens claim for discrimination under Davis v. Passman. “The elements of, and the defenses to, a federal cause of action,” the Supreme Court has emphasized, “are defined by federal law.” Howlett v. Rose, 496 U.S. 356, 375 (1990); see also Chesapeake & Ohio Ry. Co. v. Kuhn, 284 U.S. 44, 46– 47 (1931). So determining whether an immunity defense applies here is “a question of federal law.” Martinez v. California, 444 U.S. 277, 284 n.8 (1980) (quoting Hampton v. City of Chicago, 484 F.2d 602, 607 (7th Cir. 1973)). The Supreme Court has not resolved whether, in an individual-capacity action arising under federal law, an Indian tribe may confer on its officials absolute immunity from damages liability—beyond what federal law provides. And the parties have identified no case, and we have found none, in which a federal court of appeals concluded that a tribe could do so. Davis also does not guide our inquiry. In Davis, we considered a tribal official’s immunity from only a state tort claim; the plaintiff’s suit had no federal cause of action. See 398 F.2d at 83–84. And our holding did not purport to rest on the basis that federal common law entitled the tribal  ERWINE V. WESTBROOK 21 official to immunity. To the contrary, our bottom-line conclusion relied on a “prediction” about whether the Navajo Tribe’s conferral of absolute immunity on its officials would apply in Arizona state court. See id. at 84– 86. As the Tribal Officers concede, Davis answered this question “on state law grounds” by making a “prediction . . . that an Arizona court, as a matter of comity, would likely choose to honor the immunity the Navajo Nation had bestowed.” But the Tribal Officers do not contend that federal law should merely recognize the Tribe’s conferral of absolute immunity out of comity. They instead claim that such a conferral entitles them to absolute immunity by its own force. Because Davis did not address whether a tribe’s immunity statute controls when a plaintiff brings a federal cause of action, this precedent does not, as the Tribal Officers urge, “resolve this case.” That returns us to the proper test for evaluating an absolute immunity defense to a federal cause of action. “We are ‘bound not only by the holdings of [the Supreme Court’s] decisions but also by their mode of analysis.’” United States v. Van Alstyne, 584 F.3d 803, 813 (9th Cir. 2009) (alteration in original) (quoting Miller v. Gammie, 335 F.3d 889, 900 (9th Cir. 2003) (en banc)). When a defendant claims absolute immunity and no “express constitutional or statutory enactment” provides otherwise, see Forrester, 484 U.S. at 224, the Supreme Court has instructed us to take a “functional approach” in which we “conduct ‘a considered inquiry into the immunity historically accorded the relevant official at common law and the interests behind it,’” see Rehberg, 566 U.S. at 363 (quoting Imbler v. Pachtman, 424 U.S. 409, 421 (1976)). That mode of analysis governs the inquiry for each of Erwine’s federal claims. See Acres Bonusing, 17 F.4th at 906, 915–16 (finding tribal official 22 ERWINE V. WESTBROOK defendants were entitled to absolute immunity because they performed judicial or quasi-judicial functions, when the suit included a federal cause of action); Fry v. Melaragno, 939 F.2d 832, 834–36, 835 n.6 (9th Cir. 1991) (employing the functional approach in a Bivens action); see also Savage v. Maryland, 896 F.3d 260, 267–70 (4th Cir. 2018) (applying the functional approach to claims brought under 42 U.S.C. §§ 1981 and 1985); Runs After v. United States, 766 F.2d 347, 354–55 (8th Cir. 1985) (employing the functional approach in an action against tribal officials under 42 U.S.C. § 1985). Applying the functional approach, the Tribal Officers are not entitled to absolute immunity. The Tribal Officers recognize that Erwine’s claims challenge their conduct involving “personnel management actions, including supervising [Erwine], investigating his misconduct, and terminating his employment.” But the Tribal Officers do not develop, or support with authority, any argument that courts historically recognized these functions as absolutely immune from civil liability at common law. Nor could they. The Supreme Court has explained that “personnel decisions” do not give rise to absolute immunity because officials act “in an administrative capacity” when they demote or discharge an employee. See Forrester, 484 U.S. at 229. Thus, under the functional approach, absolute immunity does not bar Erwine’s federal claims against the Tribal Officers in their individual capacities. The Tribal Officers urge an altogether different analysis. As noted, they contend that the functional approach does not govern here. Their argument relies on Davis, and specifically on our observation there that tribes as “sovereign[s]” can “bestow” absolute immunity on their officials. 398 F.2d at 84. Because Congress has not  ERWINE V. WESTBROOK 23 diminished tribes’ sovereign ability to confer immunity, the Tribal Officers press that tribes retain authority to bestow absolute immunity on their officials from any and all claims implicating areas of tribal control. It is true that “unless and ‘until Congress acts, the tribes retain’ their historic sovereign authority.” Bay Mills, 572 U.S. at 788 (quoting Wheeler, 435 U.S. at 323). But tribal sovereignty reflects “the power of regulating their internal and social relations,” Santa Clara Pueblo, 436 U.S. at 55 (quoting United States v. Kagama, 118 U.S. 375, 381–82 (1886)), including the “power to make their own substantive law in internal matters” and “to enforce that law in their own forums,” id. at 55–56. Retained tribal sovereignty does not include the power to immunize tribal employees from liability for violations of federal law—whether in connection with suits expressly authorized by Congress or a Bivens cause of action implied under the Constitution. Our conclusion on this point is reinforced by the Supreme Court’s decision in Lewis, which teaches that a “tribe’s sovereign immunity is not implicated” in suits brought against tribal employees in their individual capacities. See 581 U.S. at 158. Because a tribe’s retained sovereignty does not shield tribal employees from liability in individual-capacity actions, we fail to see how a tribe could nevertheless invoke its sovereignty to enact a statute that accomplishes the same end. Accepting the Tribal Officers’ position would undermine Lewis’s holding by allowing a tribe to effect indirectly through tribal law—by bestowing absolute immunity on all its officials—what the Court has instructed its sovereign immunity does not afford. And the Tribal Officers provide no authority to support the proposition that a tribe may unilaterally create a defense to a federal cause of action for tribal officers. 24 ERWINE V. WESTBROOK Our conclusion is also in harmony with the rule that States cannot confer immunity on their employees so as to shield