The long-running Duncan v. Bonta case — a decade-old legal battle challenging California’s ban on magazines holding more than 10 rounds — is once again making national headlines. This case, which questions the constitutionality of California’s magazine restrictions, has officially entered a new phase as the state files its opposition brief to the U.S. Supreme Court.

Originally filed nearly ten years ago, Duncan v. Bonta has become one of the most significant Second Amendment cases in the country. U.S. District Judge Roger T. Benitez twice ruled that California’s ban violates the Second Amendment, calling it unconstitutional. However, both times the Ninth Circuit Court of Appeals reversed his ruling, claiming the ban is lawful and that such magazines are not even protected under the Second Amendment.

After the Supreme Court’s Bruen decision reshaped the landscape of gun law analysis in 2022, the high court sent the case back to the Ninth Circuit for reconsideration. But once again, the Ninth sided with the state — pushing Duncan back toward the Supreme Court for a second time.

Since the case was re-petitioned in August 2025, Duncan v. Bonta has received unprecedented nationwide support. Over half of U.S. state attorneys general have filed amicus briefs urging the Supreme Court to take up the case. Major Second Amendment organizations have also rallied behind the challenge, emphasizing that if Duncan succeeds, it could invalidate magazine bans nationwide — a historic victory for gun rights.

Earlier today, California filed its long-awaited opposition brief, urging the Supreme Court not to review Duncan. The state argues that the Court has recently denied similar cases, such as Ocean State Tactical v. Rhode Island and Hanson v. District of Columbia, and should do the same here.

Essentially, California’s position is that there’s no need to revisit the issue, even though Duncan arises from a final judgment rather than an interim decision. Critics call these arguments “laughable,” pointing out that California appears to be stalling to protect its restrictive gun laws and avoid a precedent that could strike down magazine bans nationwide.

Now that California has filed its opposition, the Supreme Court can move forward to conference the case — a process where justices decide whether to grant or deny review. If accepted, Duncan v. Bonta could become one of the most consequential Second Amendment cases since Bruen.

A ruling in favor of Duncan could mean millions of law-abiding gun owners in California and across the U.S. regain access to standard-capacity magazines — ending a decade-long legal saga.