Gun Control Definition: Laws, Buyers, and Restricted Firearms

In U.S. law, the gun control definition covers any rule that regulates who may own a firearm, what kinds of firearms civilians may possess, and where and how those weapons may be carried, sold, or stored. It is not one statute or one policy. It is a layered system of federal laws, state laws, and administrative rules, all operating inside the boundary the Second Amendment sets.

What the Term Actually Covers

Gun control, as a legal concept, reaches the entire lifecycle of a firearm. That includes the licensing system dealers must follow, the background checks buyers must pass, the categories of people barred from ownership, the technical rules on what features a weapon can have, the marking requirements that let law enforcement trace it, and the restrictions on where a lawfully owned gun can go.

These rules sit at the intersection of public safety and constitutional rights. Every firearm regulation has to survive Second Amendment scrutiny, which is why gun control law shifts more often than most regulatory fields. A rule that stands today may be challenged tomorrow, and a rule struck down in one circuit may still be enforced in another.

The Constitutional Boundary

The Second Amendment states that “the right of the people to keep and bear Arms, shall not be infringed.” For most of American history, courts read that as tied to militia service. In 2008, the Supreme Court held in District of Columbia v. Heller that the Amendment protects an individual right to possess a firearm for traditionally lawful purposes such as self-defense in the home.¹ The Court was equally clear that this right has limits.

In 2022, the Court sharpened the test. In New York State Rifle & Pistol Association v. Bruen, the justices ruled that when the Second Amendment’s plain text covers a person’s conduct, that conduct is presumptively protected, and the government must justify any restriction by showing it is consistent with the nation’s historical tradition of firearm regulation.² Modern regulations are now measured against analogous laws from the founding era or the nineteenth century, and much current litigation turns on how close a historical analogue has to be.

Who Cannot Legally Possess a Firearm

Federal law identifies nine categories of prohibited persons under 18 U.S.C. § 922(g). These bars apply nationwide, regardless of state law.³

Anyone convicted of a crime punishable by more than one year in prison, regardless of the actual sentence imposed.
Fugitives from justice, meaning anyone with an active warrant or fleeing prosecution.
Anyone who currently uses or is addicted to a controlled substance.
Anyone formally found by a court or other authority to be a danger to themselves or others due to mental illness, or anyone involuntarily committed to a mental institution.
Noncitizens who are in the country unlawfully, along with most nonimmigrant visa holders.
Anyone discharged from the military under dishonorable conditions.
Former U.S. citizens who have formally renounced their citizenship.
Anyone subject to a qualifying domestic violence protective order issued after a hearing with notice and an opportunity to participate.
Anyone convicted of a misdemeanor crime of domestic violence.

A prohibited person who possesses a firearm faces up to 15 years in federal prison.⁴ Most people in these categories are screened out at the point of sale, but the statute also criminalizes ongoing possession by anyone who falls into a category, even if they acquired the weapon years earlier.

How Purchases Are Screened

Every sale by a licensed dealer runs through the National Instant Criminal Background Check System (NICS), created by the Brady Handgun Violence Prevention Act of 1993. The dealer submits the buyer’s identifying information, and NICS checks it against three federal databases covering criminal history, active warrants and protection orders, and records of people specifically flagged as prohibited under federal or state law.⁵

Most responses come back almost instantly. When the system needs more time, federal law gives the FBI three business days to complete the review; if those three days pass without a final answer, the dealer is legally permitted to complete the sale.³ This default-proceed rule occasionally lets a would-be denial slip through before the check finishes.

Enhanced Checks for Buyers Under 21

The Bipartisan Safer Communities Act of 2022 added an extra layer for buyers between 18 and 20 years old. NICS examiners must contact the buyer’s state juvenile justice system, mental health adjudication records, and local law enforcement to look for disqualifying history that would not appear in the standard federal databases.⁶ If those inquiries turn up a potential issue, the review window extends from three to up to ten business days before the default-proceed rule kicks in.³

The Private-Sale Gap

Federal law requires a background check only when the seller holds a Federal Firearms License. Someone selling a gun from a personal collection generally is not required to run a check, though a growing number of states have enacted universal background check laws to close this gap. A 2024 ATF rule sharpened the line between casual seller and someone “engaged in the business” of dealing, which triggers the FFL requirement: selling firearms with the intent to predominantly earn a profit is now presumed to be dealing, regardless of volume.⁷

Which Firearms Are Regulated

Beyond controlling who can buy, federal law also controls what is available. The National Firearms Act of 1934 subjects certain categories to registration and a $200 transfer or manufacturing tax.⁸ Those categories include machine guns, short-barreled rifles and shotguns, silencers (also called suppressors), destructive devices, and a catch-all for certain concealable weapons. Possessing an unregistered NFA item is a federal felony punishable by up to 10 years.⁹

The Gun Control Act of 1968 built the broader commercial framework, requiring anyone in the business of dealing, manufacturing, or importing firearms to obtain a license.¹⁰ It also established the first federal list of prohibited persons and restricted interstate sales.¹¹

The term “assault weapon” has no single federal definition. When used in legislation, it typically refers to semi-automatic firearms with certain military-style features such as folding stocks, pistol grips, or threaded barrels. The federal assault weapons ban expired in 2004 and has not been renewed, though several states maintain their own bans with varying definitions.

Privately Made and Ghost Guns

Federal law has long allowed individuals to make firearms for personal use without marking or registering them. Partially finished parts kits, sometimes called 80-percent receivers, produced a market for weapons that could be built at home with no serial number and no background check. Law enforcement calls these untraceable weapons ghost guns. In 2022, ATF issued a rule clarifying that parts kits and unfinished frames or receivers that can readily be converted into functional firearms fall within the Gun Control Act’s definition of “firearm” and must carry serial numbers when sold commercially. The Supreme Court upheld that rule in 2025 in Bondi v. VanDerStok.¹²

Where Firearms Can and Cannot Go

Even a lawfully owned firearm cannot go everywhere. Gun control includes a patchwork of location-based restrictions at both the federal and state level.

Carry Laws

Open carry, where the weapon is visible, and concealed carry, where it is hidden on the person, are regulated separately in most states. Permit requirements, fees, and training mandates vary widely. After Bruen struck down New York’s requirement that applicants demonstrate a special need for self-defense, many states rewrote their concealed carry frameworks to comply with the historical-tradition test.²

Gun-Free Zones

Federal law prohibits firearm possession on school grounds or within 1,000 feet of a public or private elementary or secondary school, with exceptions for people licensed by the state, firearms that are unloaded and locked in a container, and certain other limited circumstances.³ Beyond schools, states commonly designate courthouses, government buildings, polling places, bars, and airports as gun-free zones, with specifics and penalties varying by jurisdiction.

Transport and Storage

Moving a firearm through different jurisdictions can be legally complicated. Many states require that a transported firearm be unloaded and secured in a locked container, separated from ammunition. Federal law offers some protection for travelers passing through restrictive states, but only if the firearm is lawful at both origin and destination and is properly stored during transit. Safe storage laws in a growing number of states also require owners to secure firearms with trigger locks or in safes to prevent access by minors or other unauthorized people.

Straw Purchasing, Trafficking, and Red Flag Laws

Two newer pieces sit inside the modern definition of gun control. First, the Bipartisan Safer Communities Act created dedicated federal crimes for straw purchasing and firearms trafficking. Under 18 U.S.C. § 932, knowingly buying a firearm for a prohibited person or for someone who intends to use it in a felony or drug crime carries up to 15 years, rising to 25 if the weapon is actually used in a felony, an act of terrorism, or a drug trafficking crime.¹³ Section 933 separately makes it a federal crime to knowingly transfer a firearm to someone who would commit a felony by receiving it.¹⁴

Second, roughly half the states have adopted some form of extreme risk protection order, commonly called a red flag law. These allow family members, law enforcement, or in some states other designated people to petition a court to temporarily remove firearms from someone in crisis. There is no federal red flag law, but the Bipartisan Safer Communities Act provided funding to help states establish or improve their own programs. Whether these orders survive under Bruen is an active question in the lower courts.

How the Layers Fit Together

Gun control is not a single law or a single idea. Federal law sets the floor: prohibited persons, dealer licensing, NICS, NFA categories, and the new trafficking statutes. States build on top of that floor with their own rules on carry permits, assault weapon definitions, private sales, storage, and red flag procedures. Courts then decide whether each layer survives Second Amendment scrutiny under the historical-tradition test. Because that landscape shifts frequently, any specific rule described here should be checked against current law before you rely on it.

1
Justia Law. District of Columbia v. Heller, 554 U.S. 570 (2008)
2
Supreme Court of the United States. New York State Rifle and Pistol Association Inc. v. Bruen, 597 U.S. 1 (2022)
3
Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts
4
Office of the Law Revision Counsel. 18 USC 924 – Penalties
5
Federal Bureau of Investigation. NICS Enhanced Background Checks for Under-21 Gun Buyers Showing Results
6
Congress.gov. Text – S.2938 – Bipartisan Safer Communities Act
7
Bureau of Alcohol, Tobacco, Firearms and Explosives. Final Rule – Definition of Engaged in the Business as a Dealer in Firearms
8
Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act
9
Office of the Law Revision Counsel. 26 USC 5871 – Penalties
10
Office of the Law Revision Counsel. 18 USC 923 – Licensing
11
Bureau of Alcohol, Tobacco, Firearms and Explosives. Gun Control Act
12
Congress.gov. Supreme Court Upholds ATF Ghost Gun Regulation in Bondi v. VanDerStok
13
Office of the Law Revision Counsel. 18 USC 932 – Straw Purchasing of Firearms
14
Office of the Law Revision Counsel. 18 USC 933 – Trafficking in Firearms