In Illinois, you can hold a medical cannabis card and keep your Firearm Owner’s Identification card and concealed carry license, but federal law still treats you as a prohibited person who cannot legally buy or possess a firearm or ammunition. The two systems contradict each other, and that conflict has not been resolved. A Supreme Court case argued in March 2026 could change the federal side of the equation, but until it is decided, the risk is real.
What Illinois Allows
Illinois requires a FOID card, issued by the Illinois State Police, to own a firearm or ammunition. The ISP states on both its FOID and Concealed Carry License pages that “Medical Marijuana Licenses are state-issued and cannot result in the denial of any right or privilege.”1Illinois State Police. Firearm Owner’s Identification Your application will be processed, your card will issue, and an existing card will stay active regardless of your medical cannabis status.2Illinois State Police. Concealed Carry License
The FOID Card Act defines “addicted to narcotics” as a disqualifying condition but carves out an exception for use of a prescribed controlled substance under the direction of a physician. A patient using medical cannabis as directed by a certifying physician falls within that exception at the state level.
That protection stops at the state line of enforcement. The ISP warns applicants on the same pages that “under Federal law, you are subject to restrictions that prohibit you from acquiring or possessing firearms and firearms ammunition.”1Illinois State Police. Firearm Owner’s Identification
Why Federal Law Says No
Marijuana remains a Schedule I controlled substance under federal law, a category reserved for drugs the federal government treats as having no accepted medical use.3Office of the Law Revision Counsel. 21 US Code 812 – Schedules of Controlled Substances The Gun Control Act makes it illegal for any person who is “an unlawful user of or addicted to any controlled substance” to possess a firearm or ammunition.4Office of the Law Revision Counsel. 18 US Code 922 – Unlawful Acts
Because federal law recognizes no lawful use of marijuana, every user is by definition an “unlawful user.” There is no exception for state-authorized medical patients, no dosage threshold, and no carveout for people who never use cannabis while handling a firearm. The ATF lists users of controlled substances among the categories of people federally prohibited from possessing firearms.5Bureau of Alcohol, Tobacco, Firearms and Explosives. Identify Prohibited Persons
Buying From a Dealer: The Form 4473 Trap
Any purchase from a federally licensed dealer requires ATF Form 4473, a sworn federal document. Question 21.e. asks whether you are “an unlawful user of, or addicted to, marijuana or any depressant, stimulant, narcotic drug, or any other controlled substance.”6Bureau of Alcohol, Tobacco, Firearms and Explosives. Firearms Transaction Record – ATF Form 4473 The form carries a bold warning that marijuana use remains unlawful under federal law regardless of state legalization.
Answer yes, and the dealer denies the sale. Answer no while holding a medical cannabis card or actively using marijuana, and you have made a false statement on a federal form, a separate felony. There is no third option.
Private Sales
Illinois requires private sellers to verify the buyer’s FOID card through the ISP, and the system will approve a verified medical cannabis patient. No Form 4473 is involved. But the federal prohibition targets the possession itself, not the purchase method. A private transfer avoids the false-statement problem on the form; it does not make the possession legal under federal law.
Guns You Already Own
A common misconception is that the federal rule only blocks new purchases. It does not. The statute prohibits an unlawful user of a controlled substance from possessing firearms or ammunition at all.4Office of the Law Revision Counsel. 18 US Code 922 – Unlawful Acts If you own firearms before enrolling in the medical cannabis program, federal law technically requires you to divest while you remain an active user.
Illinois will not require you to surrender anything. A federal agent or prosecutor who learned you possessed firearms while actively using marijuana would have the statutory basis to charge you, no matter what Illinois allows.
Federal Penalties If You Are Charged
Two federal crimes apply. Possessing a firearm as an unlawful user of a controlled substance now carries up to 15 years in federal prison, raised from 10 by the Bipartisan Safer Communities Act of 2022. Lying on Form 4473 is punishable by up to 5 years and fines.7Office of the Law Revision Counsel. 18 US Code 924 – Penalties
Federal prosecutors rarely pursue medical cannabis patients who quietly possess firearms at home, and most cases that reach federal court involve other criminal conduct. Rarely prosecuted is not legal, though, and your risk shifts the moment you have contact with federal agents for any reason.
When the Federal Restriction Lifts
According to the Illinois State Police, the federal restriction ends on the later of two events: you surrender or let your medical cannabis card expire, and one year passes since your last use of cannabis.1Illinois State Police. Firearm Owner’s Identification Both conditions have to be satisfied. Surrender your card today after using cannabis last week, and you remain a prohibited person for another year. Stop using cannabis 18 months ago but keep an active card, and you remain prohibited until you relinquish it.
Once both are met, you are no longer an unlawful user under federal law, and you can truthfully answer no on Form 4473. There is no formal certification process; the restriction expires on the ISP’s timeline.
A Pending Supreme Court Case Could Change This
The constitutionality of 18 U.S.C. ยง 922(g)(3), the federal ban on firearm possession by drug users, is before the Supreme Court in United States v. Hemani.8Oyez. United States v Hemani The case comes out of Texas, where a federal trial judge dismissed the gun charge against a man found with a pistol, marijuana, and cocaine, and the Fifth Circuit agreed the statute was unconstitutional as applied.
Oral arguments were held March 2, 2026. Several justices questioned the government’s position. Justice Amy Coney Barrett pressed the dangerousness rationale, and Justice Neil Gorsuch pointed out that the government had not defined what counts as a “user” under the statute. A decision is expected before the term ends in mid-2026. If the Court strikes down or narrows the law, the federal conflict for Illinois medical cannabis patients could disappear. If it upholds the statute, the current landscape stays in place.
Until then, Illinois will not take your card or your gun, and federal prosecutors have every tool they need if they decide to act.