The Second Amendment is more than 220 years old. When it was written, the world did not have machine guns, assault rifles, or tanks, instead relying on clunky muskets that were a pain to reload.

Yet as a video from States United to Prevent Gun Violence points out, America's lax gun laws are often based on a reading of the Second Amendment that makes it hard to pass restrictive gun laws, even as our weapons get much, much deadlier.

Warning: Graphic content:

Although it doesn't state this explicitly, the video also exposes one of the more absurd arguments in favor of the Second Amendment: Many Americans believe the right to bear arms offers protection from a potentially tyrannical government. But while granting private citizens the right to own guns in 1791 may have created some symmetry between the government and the people — both would fight with horses and muskets — that's not true anymore. Guns owned by civilians have gotten more powerful, and weapons the government uses have gotten even more powerful. So the guns interpreted to be legal under the Second Amendment would fall far, far short of the incredible arsenal the US military uses today.

Still, many legal scholars argue that the Second Amendment has been misinterpreted in recent decades. According to this view, the Second Amendment wasn't about letting individuals bear arms, but about individuals in state militias — so it was supposed to secure the ability of states, not private citizens, to arm themselves.

Former US Supreme Court Justice John Paul Stevens captured this argument in the Washington Post:

The first 10 amendments to the Constitution placed limits on the powers of the new federal government. Concern that a national standing army might pose a threat to the security of the separate states led to the adoption of the Second Amendment, which provides that "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." For more than 200 years following the adoption of that amendment, federal judges uniformly understood that the right protected by that text was limited in two ways: First, it applied only to keeping and bearing arms for military purposes, and second, while it limited the power of the federal government, it did not impose any limit whatsoever on the power of states or local governments to regulate the ownership or use of firearms. Thus, in United States v. Miller, decided in 1939, the court unanimously held that Congress could prohibit the possession of a sawed-off shotgun because that sort of weapon had no reasonable relation to the preservation or efficiency of a "well regulated Militia." When I joined the court in 1975, that holding was generally understood as limiting the scope of the Second Amendment to uses of arms that were related to military activities. During the years when Warren Burger was chief justice, from 1969 to 1986, no judge or justice expressed any doubt about the limited coverage of the amendment, and I cannot recall any judge suggesting that the amendment might place any limit on state authority to do anything.

Organizations like the National Rifle Association disagreed with this position, mounting vigorous campaigns to change public and scholarly interpretations of the Second Amendment. It worked, culminating in Supreme Court decisions in 2008 and 2010 that for the very first time acknowledged an individual's rights to bear arms for self-defense.

The recency of these rulings may be surprising to many Americans, who think the Second Amendment's individual protections have been accepted as fact for much longer than the 2008 and 2010 decisions suggest. But it took more than 200 years for the Supreme Court to explicitly acknowledge the individual rights, changing just how far governments can go when restricting access to guns.

Watch: America's gun problem, explained in 90 seconds