Whether a person with a medical marijuana card can legally buy or own a firearm depends mostly on federal law—not state law—and that is where the conflict begins.

Under the Gun Control Act, 18 U.S.C. § 922(g)(3) makes it illegal for any person who is an “unlawful user of or addicted to any controlled substance” to possess firearms or ammunition. Because marijuana remains a Schedule I controlled substance at the federal level, medical use that is perfectly legal in many states is still considered “unlawful” under federal law.

ATF’s Position on Medical Marijuana Card Holders

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has taken a consistent and firm stance. In a 2011 open letter sent to every Federal Firearms Licensee (FFL), the agency stated that anyone who uses marijuana—“regardless of whether his or her State has passed legislation authorizing marijuana use for medicinal purposes”—is considered a prohibited person under federal law.

ATF also views a state-issued medical marijuana card as evidence that the individual is a current marijuana user. Under this interpretation, a firearms dealer has “reasonable cause to believe” that the buyer is prohibited, meaning the dealer cannot legally transfer a firearm to that person.

This position appears again on ATF Form 4473, which every firearm purchaser must complete. The form asks whether the buyer is an unlawful user of marijuana or other controlled substances and warns explicitly that marijuana is illegal under federal law “regardless of whether it has been legalized or decriminalized for medicinal or recreational purposes” in the purchaser’s state. Providing false information on this form is a federal felony.

Court Decisions So Far

Courts have historically supported this federal restriction. In Wilson v. Lynch (2016), the Ninth Circuit Court of Appeals ruled that federal authorities could lawfully bar medical marijuana card holders from purchasing firearms, even when they had no criminal convictions.

More recently, however, some courts have begun to question whether § 922(g)(3) is constitutional after the Supreme Court’s Bruen decision in 2022. The Fifth Circuit, in United States v. Daniels, ruled that applying this law to a marijuana user violated the Second Amendment. And the Supreme Court has agreed to review a similar case that challenges the federal ban.

Still, until the Supreme Court issues a ruling or Congress amends the law, § 922(g)(3) remains enforceable nationwide, except where specific cases create limited regional exceptions.

What This Means for Medical Marijuana Patients

For medical marijuana card holders, the practical implications are important:

• Using marijuana while holding a medical card currently places the individual in the category of an unlawful user under federal law.

• Under ATF rules, that status disqualifies the person from purchasing a firearm from an FFL and may expose them to federal prosecution for possessing firearms or ammunition.

• Marking “no” to the Form 4473 question regarding drug use while actively using medical marijuana is considered a felony false statement.

State laws may be more permissive, and some states do not cross-check cannabis registries against firearm systems. However, this does not change a person’s standing under federal law. Medical marijuana card holders who also own or wish to purchase firearms should seek legal guidance from a qualified attorney familiar with firearms and drug policy in their state.

Learn More: Medical Cannabis Users: Key Differences Between State and Federal Law