The Second Amendment is the provision of the U.S. Constitution that protects the right of the people to keep and bear arms. Ratified on December 15, 1791 as part of the Bill of Rights, its 27 words have been at the center of American legal argument ever since, and since 2008 the Supreme Court has read them to protect an individual right to own firearms for lawful purposes, subject to certain limits grounded in historical tradition.1National Archives. Bill of Rights
The Text
The amendment reads in full: “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”2Congress.gov. U.S. Constitution – Second Amendment James Madison introduced this language along with his broader list of proposed amendments on June 8, 1789. Congress originally sent twelve amendments to the states; ten were ratified as the Bill of Rights on December 15, 1791.3National Archives. The Bill of Rights: How Did It Happen?
The sentence has two parts, and the split matters. The opening reference to a “well regulated Militia” is often called the prefatory clause. The declaration that “the right of the people to keep and bear Arms, shall not be infringed” is the operative clause. For most of the twentieth century, courts and commentators argued about whether the first clause limited the second, tying the right to militia service, or merely explained why the right was being guaranteed. The Supreme Court did not resolve that question until 2008.
Where the Amendment Came From
The idea of an armed citizenry did not begin in America. The English Bill of Rights of 1689 declared that Protestant subjects could “have Arms for their Defence suitable to their Conditions, and as allowed by Law.”4The Avalon Project. English Bill of Rights 1689 Colonists inherited that tradition and treated firearm ownership as an ordinary attribute of a free person.
Tensions sharpened before the Revolution when British authorities moved to seize colonial gunpowder stores and disarm local populations. Colonists organized independent militias and stockpiled arms in response. That memory drove the demand for a permanent constitutional guarantee. Anti-Federalists pushed hardest for it, worried that the new federal government would weaken state militias and leave states unable to resist central overreach. The amendment was the structural answer: the people’s arms could not be legislated away.
What “Militia” Meant, and What It Means Now
In the late 1700s, the militia was not the National Guard. It was essentially the adult male population, expected to be armed and ready to serve when called. This decentralized force stood in deliberate contrast to a standing army, which many founders associated with tyranny. Congress reinforced the expectation in the Militia Act of 1792, which required enrolled citizens to appear armed at their own expense.
Federal law still defines the militia today. Under 10 U.S.C. § 246, the militia of the United States includes all able-bodied males between 17 and 45 who are citizens or have declared their intention to become citizens, plus female citizens who are members of the National Guard.5Office of the Law Revision Counsel. 10 USC 246 – Militia: Composition and Classes The statute divides that group into the organized militia (the National Guard and Naval Militia) and the unorganized militia (everyone else who qualifies). In practice, the organized militia absorbed the role citizen militias once filled, and the unorganized militia has no active function.
How the Supreme Court Has Interpreted the Amendment
Three modern decisions define the current meaning of the Second Amendment.
District of Columbia v. Heller (2008)
In District of Columbia v. Heller, the Supreme Court ruled for the first time that the Second Amendment protects an individual’s right to possess a firearm for lawful purposes, independent of any connection to militia service.6Justia U.S. Supreme Court Center. District of Columbia v. Heller, 554 U.S. 570 (2008) The 5–4 decision struck down Washington, D.C.’s near-total ban on handgun possession in the home. Justice Scalia’s majority opinion concluded that “the right of the people” refers to an individual right throughout the Bill of Rights, and that “bear Arms” meant carrying weapons for confrontation, not only organized military service.7Constitution Annotated. Amdt2.4 Heller and Individual Right to Firearms
The Court also made clear the right is not unlimited. The opinion said “nothing in our opinion should be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms.”6Justia U.S. Supreme Court Center. District of Columbia v. Heller, 554 U.S. 570 (2008) That passage has shaped every Second Amendment case since.
McDonald v. City of Chicago (2010)
Heller applied only to the federal government and federal enclaves such as D.C. Two years later, in McDonald v. City of Chicago, the Court held that the Fourteenth Amendment makes the Second Amendment fully applicable to state and local governments.8Justia U.S. Supreme Court Center. McDonald v. City of Chicago, 561 U.S. 742 (2010) Every state and municipality was now bound by the individual-right reading, and Chicago’s handgun ban fell along with D.C.’s.
New York State Rifle and Pistol Association v. Bruen (2022)
The next shift came in New York State Rifle & Pistol Association, Inc. v. Bruen. The Court struck down New York’s requirement that a permit applicant demonstrate a special need for self-defense before carrying a handgun in public. More consequentially, the decision established a new framework for evaluating firearms regulations: when the amendment’s text covers someone’s conduct, that conduct is presumptively protected, and the government must show its regulation is consistent with the nation’s historical tradition of firearms regulation.9Justia U.S. Supreme Court Center. New York State Rifle and Pistol Association Inc. v. Bruen, 597 U.S. 1 (2022)
That historical-tradition test replaced the interest-balancing approach lower courts had used, in which judges weighed a government’s regulatory interest against the burden on gun rights. After Bruen, the question is whether there is a historical analogue from the founding era or the period when the Fourteenth Amendment was ratified. The shift triggered a wave of challenges to federal and state firearms laws.
The Limits the Court Has Recognized
Federal law prohibits several categories of people from possessing firearms or ammunition under 18 U.S.C. § 922(g), including convicted felons, fugitives, unlawful drug users, people adjudicated as mentally defective or committed to a mental institution, certain noncitizens, people dishonorably discharged from the military, individuals under qualifying domestic violence restraining orders, and anyone convicted of a misdemeanor crime of domestic violence.10Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts Violations carry a penalty of up to 10 years in federal prison.11U.S. Department of Justice. Quick Reference to Federal Firearms Laws
Several of these categories are now the subject of active constitutional challenges under the Bruen test, and the Supreme Court addressed one directly in 2024. In United States v. Rahimi, the Court upheld the federal ban on firearm possession by people subject to domestic violence restraining orders. The holding was narrow: when a court has found that someone poses a credible threat to the physical safety of an intimate partner, that person can be temporarily disarmed consistent with the Second Amendment.12Justia U.S. Supreme Court Center. United States v. Rahimi, 602 U.S. ___ (2024) Chief Justice Roberts, writing for the majority, said historical firearms laws have long included provisions to disarm people who threaten others with physical harm. He also clarified that the Bruen test was “not meant to suggest a law trapped in amber”: the government does not need to find a founding-era regulation that is an exact match, only an analogue resting on the same underlying principle.
The Federal Laws That Regulate Firearms
Two statutes form the backbone of federal firearms regulation and operate alongside the Second Amendment.
The National Firearms Act of 1934 imposed registration requirements and a tax on certain categories of weapons, including machine guns, short-barreled rifles and shotguns, silencers, and destructive devices. Possessing an unregistered weapon covered by the Act is a federal crime.13Congress.gov. The National Firearms Act and P.L. 119-21: Issues for Congress The Act did not ban these weapons outright but made them significantly harder to obtain.
The Gun Control Act of 1968 created the federal firearms dealer licensing system, requiring anyone in the business of selling firearms to hold a license. It also prohibited interstate sales to non-dealers and established the original prohibited-persons categories that § 922(g) later expanded.10Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts Since 1998, every purchase from a licensed dealer has required a background check through the National Instant Criminal Background Check System, run by the FBI.14Federal Bureau of Investigation. Firearms Checks (NICS) Private sales between unlicensed individuals are not subject to this federal check in most states, though a growing number of states have enacted their own laws closing that gap.
Two Tracks of Modern Firearms Litigation
Not every firearms case in the Supreme Court is a Second Amendment case. In Garland v. Cargill (2024), the Court held that a semiautomatic rifle fitted with a bump stock is not a “machinegun” under the National Firearms Act because it does not fire more than one shot “by a single function of the trigger.”15Supreme Court of the United States. Garland v. Cargill, 602 U.S. ___ (2024) The 6–3 decision, written by Justice Thomas, turned on statutory interpretation rather than constitutional doctrine. The Court concluded that the ATF had exceeded its authority by stretching the definition of “machinegun” beyond what Congress wrote, and that any change would need to come through legislation.
Together, Rahimi and Cargill illustrate the two tracks that modern firearms litigation follows. Constitutional challenges under the Second Amendment are tested against historical tradition. Regulatory challenges may turn on whether an agency has accurately interpreted the statute Congress passed. Both tracks remain active, with dozens of lower court cases working through questions that Heller, McDonald, and Bruen left open.