Binary triggers are legal under federal law, but roughly 17 states and Washington, D.C. ban them, so whether you can legally own one comes down to your state. A binary trigger fires one round when you pull and a second when you release, doubling the practical rate of fire of a semi-automatic firearm without converting it to full auto. Federal law treats each of those actions as a separate shot, which keeps the device outside the statutory definition of a machine gun. State law is where the real restrictions live.
Why Federal Law Allows Binary Triggers
The controlling statute is 26 U.S.C. § 5845(b), which defines a machine gun as any weapon that shoots more than one shot “automatically” by “a single function of the trigger.”1Office of the Law Revision Counsel. 26 USC 5845 – Definitions A binary trigger doesn’t meet that definition. It requires two distinct physical actions: a pull and a release. Each action produces one shot, so neither one fires more than one shot. The ATF has historically agreed with that reading, and firearms equipped with binary triggers have not been classified as machine guns federally.
The Supreme Court’s 2024 decision in Garland v. Cargill reinforced this interpretation. The Court struck down the ATF’s bump stock ban and defined “function of the trigger” as the mechanical action by which the trigger activates the firing mechanism.2Supreme Court of the United States. Garland v. Cargill, No. 22-976 The case involved bump stocks, not binary triggers, but its narrow reading of the statute strengthens the federal position of binary triggers. If a bump stock that simulates automatic fire doesn’t meet the machine gun definition, a device that produces one shot per deliberate physical action almost certainly doesn’t either.
How the Device Works
The mechanical detail matters because it’s the reason for the legal outcome. A standard semi-automatic trigger fires once when pulled and does nothing on release. A binary trigger replaces the factory fire-control group with an assembly that includes a specialized disconnector: the pull fires the first round, and when the trigger moves forward on release, the disconnector releases the hammer to fire a second.
Most binary triggers include a three-position selector: safe, semi-automatic, and binary. The semi-auto position works like a factory trigger. The binary position enables the pull-and-release cycle. That selector also functions as a safety. If you pull in binary mode and decide you don’t want the release shot, you can hold the trigger back, flip the selector to semi-auto, and then release without firing.3Franklin Armory. BFSIII AR Waiver and Manual Practicing that cancellation is one of the fundamental safety skills for running one of these systems.
States That Ban Binary Triggers
Federal legality doesn’t help if your state prohibits the device. As of early 2025, roughly 17 states and Washington, D.C. ban binary triggers. The list includes California, Connecticut, Delaware, Hawaii, Illinois, Iowa, Maryland, Minnesota, New Jersey, New York, Rhode Island, Virginia, and Washington, among others. The list shifts. In August 2025, a Minnesota judge struck down that state’s 2024 binary trigger ban on state constitutional grounds.4Minnesota Reformer. Judge Strikes Down Minnesotas Binary Trigger Ban, Suggests Invalidating 2024 Omnibus Bill
States write these bans in different ways, and the language matters if you’re trying to figure out whether your state’s law reaches the device you’re looking at:
- Some states, like Rhode Island, explicitly name binary triggers alongside bump stocks and trigger cranks.
- Illinois uses broader language that bans any device designed to increase the rate of fire of a semi-automatic weapon, which captures binary triggers without naming them.
- New York folds them into a “rapid-fire modification device” category.
- New Jersey adds them to its definition of machine guns.
- Connecticut treats possession as a Class D felony.
- California bans what it calls “multiburst trigger activators” and punishes violations with up to one year in county jail or a longer prison sentence.5California Legislative Information. California Penal Code PEN 32900
The remaining roughly 33 states have no specific prohibition, so binary triggers are legal there to the same extent semi-automatic firearms are. That’s not a permanent condition. Firearms legislation moves every session, and any state could add restrictions. Verify current state law before buying or possessing one.
What Happens If a Device Gets Reclassified
Classifications can change, and the penalties if a device you own ends up on the wrong side of the line are severe. Under the National Firearms Act, any violation carries a fine of up to $10,000, imprisonment of up to ten years, or both.6Office of the Law Revision Counsel. 26 USC 5871 – Penalties Separately, 18 U.S.C. § 922(o) makes it a federal crime for any civilian to transfer or possess a machine gun manufactured after May 1986, with narrow exceptions for government agencies and pre-1986 registered weapons.7Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts A conviction is a permanent felony record that ends your firearm rights.
The ATF has taken this path with related devices before. It classified certain forced reset triggers as machine guns and pursued enforcement against Rare Breed Triggers.8Bureau of Alcohol, Tobacco, Firearms and Explosives. Rare Breed Triggers FRT-15s and Wide Open Triggers WOTs Return After Cargill, a federal court in Texas applied the same reasoning to FRTs and concluded they aren’t machine guns, and the Department of Justice settled the litigation.9U.S. Department of Justice. Department of Justice Announces Settlement of Litigation Between Federal Government and Rare Breed The point for a binary trigger owner is that federal classification is not static, and the penalty exposure sits behind any future shift.
Range Rules Can Prohibit Use Where Ownership Is Legal
Legal to own is not the same as legal to shoot wherever you want. Many indoor and outdoor ranges prohibit rapid fire regardless of how it’s produced. Rapid fire increases the chance of rounds striking ceiling baffles, target hangers, and lane dividers, and indoor ranges are especially strict because ricochets off structural components can reach adjacent lanes.
Range safety officers write rules for the least experienced shooter who might walk in, not for trained competitors. A binary trigger roughly doubles the rate of fire, and for someone without much trigger time that means less control over shot placement. If a range prohibits rapid fire or requires a minimum interval between shots, binary mode will violate that policy. Call ahead. Some ranges welcome binary triggers, particularly outdoor facilities that cater to competition or tactical shooters, but assuming permission is a good way to get asked to leave.
Self-Defense and Civil Liability
If you use a binary-equipped firearm in a self-defense shooting, the modification becomes part of the legal case. A prosecutor may argue that installing a device designed to increase rate of fire shows intent to cause maximum harm rather than stop a threat. Whether that argument is legally sound in your jurisdiction or not, it gives a jury something to weigh against you that wouldn’t exist with a factory trigger.
Civil liability sits alongside the criminal case. In a wrongful death or personal injury suit, the plaintiff’s attorney will examine every modification on the firearm. Aftermarket trigger enhancements can support negligence theories, particularly if the modification contributed to unintended discharges or if the shooter fired more rounds than necessary to address the threat. The trigger manufacturer, the gunsmith who installed it, and the shooter can each face separate claims.
This doesn’t mean a binary trigger makes lawful self-defense impossible. It means the modification adds complexity to a situation that is already legally high-stakes. Some firearms attorneys advise keeping any gun intended for home or personal defense in a factory or near-factory configuration for that reason.