The Second Amendment is one of the most hotly debated sections of the U.S. Constitution today. It is the one that reads: “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.” Yet for all the attention it gets among gun rights activists and gun control advocates alike, there have been relatively few Supreme Court rulings on the amendment. In Presser v. The State of Illinois, one of the earliest rulings on the Second Amendment, the Court did not question the right of individual citizens to keep and bear arms; it would be more than a century later until this question was first addressed. In Presser, instead, the Court examined the meaning of the word “militia.” Ultimately, it concluded that individual states had the right to regulate activities of armed citizens.

The first British colonists in America formed the first American militias. These militias were groups of men town leaders could called upon in emergencies to protect their town from internal or external attacks. Militias were the nucleus of the American Revolutionary War forces and, in the wake of American independence, membership in a voluntary militia became a mark of patriotism and good citizenship.

Formed independently of state or federal military structure, militias functioned more like fraternal organizations than legitimate military bodies in the years before the Civil War. Drill practice provided leisure activities for men while militias’ picnics and parades entertained members’ families and communities. When military defense was needed, militias were easily able to rally their troops, as they did during the Civil War.

Many militias that joined the war effort together disbanded in 1865. Their numbers had been decimated and survivors’ tastes for military life were surely dampened as well. But a new threat to the nation began to appear in the late 1860s and 1870s: radical labor organizations. In part because of the speed at which Chicago industrialized, the city hosted a thriving socialist community.

Battles between striking workers and police grew more frequent and more violent in the 1870s, causing Chicago’s leading businessmen to fear that the workers might attempt to rob the wealthy of their land, their homes, and even their lives. In order to protect themselves, Chicago’s very wealthiest citizens organized the First Illinois Regiment in 1874.

Meanwhile, workers were increasingly finding themselves at the wrong end of policemen’s clubs. This struggle prompted German workers to form their own militia, the Lehr und Wehr Verein (“Education and Defense Society’) in 1875. Within a year, a number of other socialist militias joined their ranks.

Membership in the socialist militias boomed after the 1877 National Railroad Strike that shut down the nation’s railway lines, destroyed $10 million in property, and left 100 people dead as troops tried to restore order. Socialist militias began drilling nearly every Sunday, with “guns sloped on the shoulder,” as the Chicago Tribune observed. Social picnics became workers’ rallies where speakers urged listeners to “actively rebel against the…laws which govern society.” The Tribune concluded that the militias who hosted these events were “hostile to all good government.”

The popularity of socialist militias after the strike fueled the fears of Chicago’s elite about class revolution. The same men who had organized the First Illinois Regiment pressed the Illinois state legislature to create a bill which stated that “any and all military organizations not organized under the Governor’s command” would be forbidden from “marching on the streets with arms or uniform.” What had once been considered a demonstration of good citizenship was now being construed as a threat, depending on the political ideology of the marchers.

Chicago’s English-language socialist newspaper claimed that the law would violate the “constitutional rights of free speech and free assemblage” of the socialist militias. One of the city’s most radical socialists argued that the law took away the rights of working people, and was applied unevenly throughout society. He claimed it was “was unconstitutional, since it was class legislation.”

Despite socialists’ protests, the bill became law in mid-1879. On July 1, the day the law went into effect, the Lehr und Wehr Verein staged a test of its constitutionality. They alerted the authorities that a group of their members would be marching, with arms, at a certain time and place. Police arrested Hermann Presser, the Commander-in-Chief of the Lehr und Wehr Verein. Presser then applied for a writ of habeus corpus, forcing the courts to determine whether or not the Illinois Militia Law was constitutional.

Presser’s lawyers argued that the militia law violated the Second and Fourteenth Amendments because “the right to keep and bear arms was a fundamental right which the [Illinois] Legislature could not take from the people under any general grant of legislative authority” and that it targeted a certain class and political ideology.

The case made its way to the United States Supreme Court by 1885. The court ruled that the Illinois Militia Law was constitutional because amendments placed limitations on the federal government. States could legislate as they chose, so long as the state legislation did not take from citizens rights which the Constitution specifically stated were theirs. The Constitution, the justices explained, protected only the right to keep and bear arms, not to form militias or drill and march with arms. It was within the rights of the states, the court ruled, to regulate the formation and activities of militias because without regulation, the government would not be able to protect itself against “assemblages organized for sedition and treason.” They declared the 1879 Illinois Militia Law constitutional.

Before the Civil War, there was little, if any, regulation by state or federal governments on the activities of militias. But as class conflict grew in the late nineteenth century and some popular militias took on ideologies that rejected existing governments, the Supreme Court set a new precedent. It declared that the government’s need to protect its own existence was the primary consideration when interpreting the Second Amendment. The Court, in a ruling that stands today, declared that individual states could regulate the activities of their armed citizens.