The Rooker-Feldman doctrine is a narrow jurisdictional rule that prevents federal courts, other than the United States Supreme Court, from acting with appellate jurisdiction over state court judgments. Miroth v. Cnty. of Trinity, 136 F. 4th 1141, 1144 (9th Cir. 2025). The doctrine applies only to "cases brought by state-court losers complaining of injuries caused by state-court judgments rendered before the district court proceedings commenced and inviting district court review and rejection of those judgments." Exxon Mobil Corp. v. Saudi Basic Indus. Corp., 544 U. S. 280, 284 (2005). To trigger the doctrine, the federal plaintiff must "both assert[] as her injury legal error or errors by the state court and seek[] as her remedy relief from the state court judgment." Miroth, 136 F. 4th at 1155.

In Miroth v. County of Trinity, the Ninth Circuit reaffirmed this narrow scope. Patricia and Stanley Miroth alleged that Trinity County officials violated their rights by failing to provide them with "social services required by state law," including a state-mandated safety plan designed to help them retain custody of their children; and by engaging in a course of deception that "defrauded the state court" into terminating their parental rights. Id. at 1151.

Although the Miroths in earlier iterations of their complaint wanted to set aside the state judgment and reinstate their parental rights, the second amended complaint removed those requests and instead sought monetary damages. Id. at 1145. The Ninth Circuit found that "the [Miroths'] claims [did] not seek relief from or reversal of the [state] court's [o]rder." This change alone was "a sufficient basis by which to conclude that the Rooker-Feldman doctrine [did] not apply." Id. at 1151.

More importantly, the Ninth Circuit emphasized that the Miroths' claims did not allege "as a legal wrong an allegedly erroneous decision by a state court," but rather the alleged wrongs -- failing to create a required safety plan and making fraudulent misrepresentations -- were "legal wrongs by adverse parties... preceding the issuance of" the state court orders. Id. As the Ninth Circuit explained, such wrongs "cannot avoid scrutiny" under Rooker-Feldman merely because they were presented to the state court and ultimately influenced its decisions. Id. at 1152. The dissent argued the Miroths had "ample opportunity" in state court to raise these fraud claims and simply lost, but the majority stressed that this was irrelevant in determining jurisdiction -- having an opportunity to litigate in state court goes to preclusion, not Rooker-Feldman. Id. at 1156.

"Rooker-Feldman does not otherwise override or supplant preclusion doctrine," nor is it "preclusion by another name." Id. at 1149. Raising matters previously litigated does not itself transform the claims into a jurisdictionally barred attack on a state court judgment; preclusion is a state-law merits defense, while Rooker-Feldman is a federal jurisdictional bar. Id. at 1156. However, because the Miroths had already raised -- or could have raised -- their fraud allegations in state court, their claims did more directly implicate preclusion than pure external fraud.

Under California's claim preclusion doctrine, "a valid, final judgment on the merits precludes parties or their privies from relitigating the same 'cause of action' in a subsequent suit." S. Cal. Stroke Rehab. Assocs. v. Nautilus, Inc., 782 F. Supp. 2d 1096, 1105 (S. D. Cal. 2011). A cause of action is defined by the "primary right" at stake. Id. When "two actions involving the same parties seek compensation for the same harm, they generally involve the same primary right," and any claims arising from it, "if not brought initially, may not be raised at a later date," including those that "could have been litigated" in the first proceeding. Id. Here, because the harm alleged in both cases was the Miroths' loss of parental rights, the same cause of action was likely at issue, and there was a final judgment on the merits, as the parties exhausted their appellate options. Since the actions also involved the same parties, it is likely that claim preclusion applies.

In contrast, issue preclusion applies only to "matters in issue or points controverted," not "to matters which might have been litigated and determined." Janjua v. Neufeld, 933 F. 3d 1061, 1065 (9th Cir. 2019). Here, the appellate opinion does not provide sufficient information to determine whether the Miroths' claims of fraud on the state court were actually and necessarily litigated so as to invoke issue preclusion.

Even with its narrow interpretation, Rooker-Feldman remains a valuable jurisdictional safeguard against blatant forum shopping, complementing substantive preclusion doctrines to ensure judicial efficiency, respect for finality, and proper channeling of disputes to the courts vested with rightful authority. Being jurisdictional, it offers a clean, decisive way to avoid, in many cases, relitigating state court adjudications or delving into the semantics of preclusion.