Duncan v. Bonta

Duncan v. Bonta (full caption: Virginia Duncan et al. v. Rob Bonta, Attorney General of California; Ninth Circuit No. 23-55805) is a long-running federal court challenge to California’s ban on large-capacity magazines (LCMs)—firearm magazines capable of holding more than 10 rounds of ammunition—under California Penal Code § 32310. 

The case centers on whether the ban violates the Second Amendment right to keep and bear arms (and secondarily, the Fifth Amendment’s Takings Clause, because the law requires owners to surrender or destroy previously lawful magazines without compensation).

Background

In 2016, California passed Senate Bill 1446 and Proposition 63, which together prohibited the manufacture, sale, purchase, transfer, and possession of LCMs (effective July 1, 2017). The law defines LCMs as any ammunition feeding device that accepts more than 10 rounds. Plaintiffs (individual gun owners including Virginia Duncan and the California Rifle & Pistol Association) sued in 2017, arguing the ban infringes on the constitutional right to use commonly owned firearms for self-defense, hunting, and other lawful purposes.

Procedural History (Key Milestones)

•  District Court (Judge Roger T. Benitez, Southern District of California): Initially struck down the ban as unconstitutional (2019), issuing injunctions.

•  Ninth Circuit: A panel initially affirmed the plaintiffs; an en banc panel reversed pre-Bruen(2021). After the Supreme Court’s New York State Rifle & Pistol Ass’n v. Bruendecision (2022), SCOTUS granted cert, vacated the ruling, and remanded for reconsideration under the new “text, history, and tradition” test.

•  Post-Bruen: The district court again invalidated the ban (2023). The Ninth Circuit stayed it and, sitting en banc, upheld the ban on March 20, 2025.

Ninth Circuit’s 2025 En Banc Holding

The court ruled (in a majority opinion by Judge Graber) that California’s law is constitutional for two independent reasons:

1.  Large-capacity magazines are not “arms” under the Second Amendment’s plain text—they are optional accessories, not weapons themselves, and firearms function without them.

2.  Even if they are protected, the ban fits within America’s “historical tradition of firearm regulation” (analogizing to historical laws restricting especially dangerous weapon uses and regulating firearm components for public safety).

The court reversed the district court and ordered judgment for the state. Strong dissents (by Judges Bumatay, Nelson, and VanDyke) argued that magazines are integral to firearms, are in common use for lawful purposes, and lack relevant historical analogues (modern magazine-capacity limits only emerged in the 20th century). 

Current Status (as of March 2026)

The plaintiffs petitioned the U.S. Supreme Court for review (Docket No. 25-198, filed August 15, 2025). The petition asks:

1.  Whether a ban on possession of “exceedingly common ammunition feeding devices” violates the Second Amendment.

2.  Whether confiscating lawfully owned property without compensation violates the Takings Clause.

The case has been relisted multiple times for Supreme Court conferences (through at least March 2026) but certiorari has not yet been granted. Recent supplemental briefs highlight a developing circuit split (e.g., the D.C. Circuit’s Benson v. United States struck down a similar ban, treating magazines as protected “arms”). No final Supreme Court decision has been issued. 

In Depth Introduction to Duncan v. Bonta

Duncan v. Bonta represents a significant legal challenge to California’s restrictions on firearm magazines, specifically those capable of holding more than ten rounds of ammunition. This case has evolved over several years, navigating through various levels of the federal judiciary and intersecting with broader debates on gun rights and public safety in the United States. At its core, the litigation questions the constitutionality of state-imposed limits on magazine capacity under the Second Amendment, which protects the right of individuals to keep and bear arms. Additionally, it touches on potential violations of the Fifth Amendment’s Takings Clause, given the requirement for owners to dispose of or surrender previously lawful property without compensation.

Background of the Legislation

The origins of the dispute trace back to 2016, when California enacted legislation aimed at curbing the proliferation of what lawmakers termed large-capacity magazines. Through Senate Bill 1446 and the voter-approved Proposition 63, the state prohibited the manufacture, importation, sale, transfer, and possession of magazines that hold more than ten rounds. This measure built upon earlier restrictions but expanded them to include outright bans on possession, effective from July 2017. Proponents of the law argued that such magazines facilitate mass shootings by allowing perpetrators to fire more rounds without reloading, thereby increasing the potential for casualties in violent incidents. They pointed to statistical data suggesting that limiting magazine size could provide critical pauses during attacks, enabling victims to escape or law enforcement to intervene.

Arguments from Plaintiffs and Defendants

Opponents, including the plaintiffs in this case—individual firearm owners such as Virginia Duncan and organizations like the California Rifle & Pistol Association—contended that these restrictions infringe upon fundamental constitutional rights. They asserted that magazines holding more than ten rounds are not exotic accessories but standard components of many commonly owned firearms used for self-defense, sport shooting, hunting, and other lawful activities. In their view, the ban disproportionately burdens law-abiding citizens while doing little to deter criminals, who are unlikely to comply with such regulations. The lawsuit was filed in the United States District Court for the Southern District of California in 2017, seeking to enjoin the enforcement of the relevant provisions of the California Penal Code.

District Court Proceedings

The district court, presided over by Judge Roger T. Benitez, played a pivotal role in the early stages of the case. In a detailed opinion issued in 2019, the court granted summary judgment in favor of the plaintiffs, declaring the ban unconstitutional. The judge emphasized that the Second Amendment encompasses the right to possess firearms in common use for lawful purposes, drawing on precedents like District of Columbia v. Heller, which struck down handgun bans in the nation’s capital. He argued that large-capacity magazines qualify as protected arms because they are integral to the functionality of many modern firearms and are owned by millions of Americans without incident. Furthermore, the court found that the state’s interest in public safety, while legitimate, did not justify a blanket prohibition that failed to survive strict scrutiny or even intermediate scrutiny under prevailing legal standards at the time.

Ninth Circuit Appeals Pre-Bruen

This ruling prompted an appeal to the Ninth Circuit Court of Appeals, where the case underwent multiple reviews. Initially, a three-judge panel affirmed the district court’s decision, but the full court, sitting en banc, reversed it in 2021. The en banc panel applied a two-step framework common in Second Amendment cases prior to a major shift in jurisprudence. Under this approach, courts first assessed whether the regulated conduct fell within the historical scope of the Second Amendment, and if so, applied an appropriate level of scrutiny based on the severity of the burden. The majority concluded that while the ban implicated protected rights, it withstood intermediate scrutiny because it was reasonably tailored to advance important governmental objectives related to reducing gun violence.

Impact of the Bruen Decision

The landscape changed dramatically with the Supreme Court’s 2022 decision in New York State Rifle & Pistol Association v. Bruen. In Bruen, the Court rejected the two-step interest-balancing test, instead mandating that firearm regulations be consistent with the nation’s historical tradition of firearm regulation. Governments must now demonstrate that modern laws are analogous to historical restrictions in both how and why they burden Second Amendment rights. Following Bruen, the Supreme Court granted certiorari in Duncan v. Bonta, vacated the Ninth Circuit’s ruling, and remanded the case for reconsideration under the new standard.

Upon remand, the district court once again invalidated the ban in 2023, applying the Bruen framework. Judge Benitez conducted an extensive historical analysis, finding no relevant tradition of regulating magazine capacity in the founding era or the 19th century. He noted that repeating firearms capable of firing multiple rounds without reloading existed as early as the 16th century, and by the time of the Second Amendment’s ratification, multi-shot weapons were known, albeit not widespread. The court concluded that California’s law lacked historical analogues and thus violated the Constitution. It also addressed the Takings Clause claim, suggesting that forcing owners to destroy or relinquish their property without just compensation constituted an impermissible taking.

Ninth Circuit’s 2025 En Banc Decision

The state appealed, and the Ninth Circuit stayed the district court’s injunction, allowing the ban to remain in effect pending resolution. In a significant development, the en banc Ninth Circuit upheld the law in a decision issued on March 20, 2025. The majority opinion, authored by Judge Susan P. Graber, offered two primary rationales for constitutionality. First, it determined that large-capacity magazines do not qualify as “arms” within the meaning of the Second Amendment’s text. Instead, they were characterized as optional accessories that enhance firearm capacity but are not essential for basic operation, as guns can function with smaller magazines or even single rounds. This interpretation narrowed the scope of protected conduct, sidestepping the need for a full historical inquiry in some respects.

Second, even assuming magazines are protected, the court found the ban consistent with historical traditions of firearm regulation. It drew analogies to laws from the colonial and early republican periods that restricted dangerous weapons or their use in ways that threatened public safety, such as prohibitions on concealed carry or limits on gunpowder storage. The majority argued that modern concerns about mass shootings parallel historical fears of public disorder, justifying regulations on firearm components that enable rapid, sustained fire. This reasoning aimed to align with Bruen’s emphasis on text, history, and tradition while upholding the state’s authority to enact measures promoting community safety.

Dissents in the Ninth Circuit

The decision was not unanimous; it drew pointed dissents from several judges. Judge Patrick J. Bumatay, joined by others, argued that magazines are inextricably linked to firearms and thus fall squarely under Second Amendment protections. He criticized the majority for artificially separating magazines from the arms they serve, likening it to regulating quills without considering ink in a First Amendment context. The dissenters conducted their own historical review, asserting that no founding-era laws imposed capacity limits, and that 20th-century restrictions are too recent to establish a tradition. They further contended that the ban fails Bruen’s test because it prohibits possession of commonly used items for self-defense, without sufficient historical precedent.

Current Status of the Case

As of early 2026, the case remains active at the highest level. The plaintiffs have petitioned the U.S. Supreme Court for certiorari, seeking review on both the Second Amendment and Takings Clause issues. The petition highlights a growing circuit split, as other federal appeals courts have reached conflicting conclusions on similar magazine bans. For instance, some circuits have struck down comparable laws, viewing magazines as protected arms without adequate historical justification for restrictions. The Supreme Court has relisted the case for multiple conferences, indicating ongoing deliberation, but has yet to grant or deny review.

US Supreme Court Involvement

The U.S. Supreme Court has played a crucial role in shaping the trajectory of Duncan v. Bonta, intervening at key junctures to influence its direction amid evolving Second Amendment jurisprudence. The Court’s first direct involvement came in 2022, following its landmark decision in New York State Rifle & Pistol Association v. Bruen. In Bruen, the justices established a new test for evaluating firearm regulations, requiring them to be consistent with the text of the Second Amendment and the nation’s historical tradition of firearm regulation, rather than relying on means-ends scrutiny. Recognizing that the Ninth Circuit’s 2021 en banc ruling upholding California’s magazine ban had applied the now-rejected two-step framework, the Supreme Court granted the plaintiffs’ petition for certiorari on June 30, 2022. However, instead of hearing the case on the merits, the Court issued a grant-vacate-remand (GVR) order, vacating the Ninth Circuit’s judgment and remanding the case back to the appeals court for reconsideration in light of Bruen. This action was part of a broader set of GVR orders issued that day for several Second Amendment cases, signaling the Court’s intent to ensure lower courts uniformly apply the new standard.

On remand, as detailed earlier, the district court reaffirmed its invalidation of the ban, leading to further appeals and the Ninth Circuit’s 2025 en banc decision upholding it once more. Dissatisfied with this outcome, the plaintiffs filed a new petition for certiorari with the Supreme Court on August 15, 2025, under Docket No. 25-198. The petition presents two primary questions for review: first, whether a state’s outright ban on the possession of commonly used ammunition magazines violates the Second Amendment, particularly under Bruen’s history-and-tradition test; and second, whether requiring owners to surrender or destroy such lawfully acquired property without compensation constitutes a violation of the Fifth Amendment’s Takings Clause. The petitioners argue that the Ninth Circuit’s narrow interpretation of “arms” to exclude magazines contradicts Bruen and prior precedents like Heller, which protect firearms and their essential components. They also emphasize the absence of historical analogues for capacity limits, noting that such regulations only appeared in the mid-20th century.

The petition further underscores a deepening circuit split on magazine bans, which could compel Supreme Court intervention to resolve inconsistencies. For example, while the Ninth Circuit upheld California’s law, the D.C. Circuit in Benson v. United States struck down a similar District of Columbia ban, holding that magazines are integral to arms and lack sufficient historical justification for prohibition. Other circuits, such as the Seventh and Third, have issued mixed rulings on analogous restrictions, creating uncertainty for gun owners and states alike. Supplemental briefs filed by the petitioners in late 2025 and early 2026 have highlighted these developments, urging the Court to grant review to provide nationwide clarity.

As of March 2026, the Supreme Court has relisted the case for consideration at multiple conferences, a procedural step that often indicates serious internal discussion but does not guarantee a grant of certiorari. Relists have occurred at least through the Court’s March 1, 2026, conference, with no decision announced yet. If certiorari is granted, oral arguments could be scheduled for the October 2026 term, potentially leading to a merits decision by June 2027. The Court’s conservative majority, which has expanded Second Amendment protections in recent years through cases like Heller, McDonald v. City of Chicago, and Bruen, may view this as an opportunity to further define the scope of permissible firearm regulations. Conversely, denial of certiorari would leave the Ninth Circuit’s ruling intact, allowing California’s ban to stand while perpetuating the circuit split. This ongoing involvement reflects the Supreme Court’s pivotal role in refereeing contentious gun rights issues, with Duncan v. Bonta poised to potentially set enduring precedents on accessory bans and property takings.

Broader Significance to Nationwide Magazine Bans and Issues

Beyond its immediate implications for California, Duncan v. Bonta holds profound significance for nationwide magazine bans and related issues. It serves as a bellwether for how courts across the country will interpret and apply the Bruen standard to restrictions on firearm accessories, potentially influencing laws in at least a dozen states—including New York, New Jersey, Colorado, and Washington—that impose similar limits on magazine capacity. A Supreme Court ruling in favor of the plaintiffs could invalidate these bans en masse, establishing that magazines exceeding ten rounds are constitutionally protected as common-use items essential for self-defense, thereby limiting states’ ability to regulate them without clear historical precedents.

Conversely, if the Court upholds the Ninth Circuit’s decision, it could embolden other jurisdictions to enact or strengthen magazine bans, providing a roadmap for framing such regulations as consistent with historical traditions of public safety measures. This would exacerbate existing disparities in gun laws across states, potentially leading to increased litigation and forum shopping by advocacy groups. The case also raises critical issues around the Takings Clause, which could set precedents for how governments must handle property rights when retroactively banning items like magazines, ammunition, or other regulated goods—possibly requiring compensation programs that add fiscal burdens to state budgets.

Moreover, Duncan v. Bonta underscores broader national debates on gun violence prevention versus individual rights, especially in the context of rising mass shootings. Its resolution could impact not just magazine bans but analogous restrictions on other firearm features, such as assault weapon definitions or bump stocks, by clarifying the scope of “arms” under the Second Amendment. In a politically divided landscape, the case highlights tensions between federal circuits, urging the Supreme Court to resolve splits that affect millions of gun owners and public safety policies. Ultimately, this litigation could redefine the balance of power between states and the federal Constitution in regulating modern firearms, with ripple effects on legislation, enforcement, and societal norms around gun ownership for decades to come.