Duncan v. Bonta: What the Supreme Court Cert Petition Could Mean for California

Quick take: The long-running challenge to California’s magazine limit law is back in the spotlight. Petitioners have filed a request for the U.S. Supreme Court to hear Duncan v. Bonta. Here’s the history, what this move means, what to expect next, and why this matters to left-leaning gun owners in California.

Table of Contents

  1. A quick history of Duncan v. Bonta
  2. What just happened: the cert petition
  3. What to expect from the Supreme Court
  4. How long the process could take
  5. Why this matters to left-leaning gun owners
  6. How a ruling could reshape California gun law
  7. What to watch next
  8. Sources

A quick history of Duncan v. Bonta

California has restricted magazines over ten rounds for years. The state expanded those rules over time, including a possession ban approved by voters in 2016. The case known as Duncan v. Bonta challenges that law under the Second Amendment and, separately, under the Takings Clause. The case has bounced between the district court, the Ninth Circuit, and the Supreme Court’s guidance after New York State Rifle & Pistol Association v. Bruen. In March 2025, a Ninth Circuit en banc panel upheld the law again, and the challengers are now asking the Supreme Court to step in.

  • Key point: The Ninth Circuit’s March 20, 2025 en banc decision sided with the state and instructed the district court to enter judgment for the Attorney General.
  • The issues: Are magazines commonly owned “arms” protected by the Second Amendment, and can the state force dispossession of previously lawful property without compensation?

For background on the law’s evolution and the state’s own summary of what changed in 2000, 2013, and 2016, see the sources below.

What just happened: the cert petition

The challengers have filed a petition for a writ of certiorari, which is the formal request asking the Supreme Court to hear the case. Earlier this summer they secured extra time to file. Advocacy groups supporting the suit report that the petition was filed in mid-August, and they’ve posted the petition text publicly.

What to expect from the Supreme Court

The Court takes only a small fraction of petitions. This one raises nationally important questions and affects millions of owners, so it will get a serious look. The justices could:

  • Deny the petition. That would leave the Ninth Circuit’s decision in place.
  • Grant the petition and set the case for full briefing and argument.
  • Hold the petition if there is a related case they want to decide first, then act on this one.

If the Court grants review, watch for the framing of the questions presented. Clarity on how Bruen applies to magazines, and whether dispossession without compensation raises a Takings problem, would be a big deal.

How long the process could take

Here is a realistic timeline if the Court grants review:

  1. Conference and grant window: a few weeks to a few months after filing.
  2. Briefing and oral argument: likely in late 2025 or early 2026.
  3. Decision: most argued cases are decided by June at the end of the term, so mid-2026 is a reasonable expectation if cert is granted.

Why this matters to left-leaning gun owners

  • Civil liberties lens: A clear ruling on whether magazines are protected “arms” sets a principled boundary that prevents overbroad, confiscatory rules while still allowing targeted safety measures.
  • Takings and fairness: If the state can force you to give up previously lawful property without compensation, that is a slippery slope. A Takings ruling that requires fairness helps everyone, not just gun owners.
  • Better policy focus: Clear constitutional guardrails push lawmakers toward data-backed strategies that target violence, trafficking, and prohibited possessors rather than blanket bans that sweep in ordinary people.
  • Consistency: A Supreme Court opinion would bring more stability. Californians have dealt with years of whiplash on what is legal to own and when.

How a ruling could reshape California gun law

Depending on what the Court does, we could see:

  • Narrow tailoring: Courts may require tighter fits between public safety goals and the burdens placed on ordinary, law-abiding owners.
  • Property rights clarity: If the Takings claim gets traction, future laws that force surrender or destruction would likely need compensation or alternative paths.
  • Ripple effects: How the Court applies Bruen to magazines will influence other cases in California touching on so-called “assault weapon” features and related rules.

What to watch next

  • Supreme Court docket updates: look for when the petition is “distributed for conference.”
  • Amicus briefs: public safety groups, civil rights groups, state coalitions, and academics will likely weigh in.
  • Any stays or interim guidance: if the Court takes the case, watch for requests about enforcement while the appeal unfolds.

Sources

  • Ninth Circuit en banc opinion, Mar. 20, 2025 (PDF). Link
  • Ninth Circuit order on en banc authority and composition, Mar. 20, 2025 (PDF). Link
  • SCOTUS docket entry for time-extension application (No. 24A1191). Link
  • Petition for Writ of Certiorari (posted by supporters) (PDF). Link
  • NRA-ILA update noting filing of the cert petition, Aug. 15, 2025. Link
  • California AG press statement on LCM and assault weapon laws, background on 2000, 2013, 2016. Link
  • Giffords Law Center summary of California LCM law. Link
  • SCOTUSblog case file overview of issues presented. Link

FAQ

Is the magazine ban still enforceable right now?

Yes. The Ninth Circuit’s en banc decision in March 2025 upheld the law. Unless a court issues a new injunction, the restrictions remain in place while the Supreme Court decides whether to hear the case.

When would we know if the Supreme Court is taking the case?

After a petition is filed, it is usually “distributed for conference” within weeks. A grant or denial can come soon after, but sometimes petitions are relisted across multiple conferences.

If the Court takes the case, when could a decision arrive?

Arguments would most likely be scheduled in late 2025 or early 2026, with a decision by June 2026 at the end of the term.

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