Adam Winkler is a professor at UCLA School of Law and the author of Gunfight: The Battle over the Right to Bear Arms in America.

Gun control is one of the great pieces of unfinished business for the Democratic Party. Although the party has never been unified in its support of restrictive gun laws – indeed, gun control historically transcends the usual party lines – for the past century Democrats have pushed for a more vigorous role for government in regulating guns. They’ve been largely unsuccessful, however, and lately Democrats have made Avoid Gun Control an informal plank in the party’s platform.

The Newtown massacre however may have changed all that.

Like health care, social security, and so many other issues central to the Democratic agenda, the party’s support for gun control stems from Franklin D. Roosevelt. For most of American history, regulation of guns was a matter of state law. State-level regulation, however, came under tremendous pressure during the 1920s and 30s, when Prohibition-era gangsters like Al Capone overwhelmed local police resources and traveling desperadoes like Bonnie and Clyde easily escaped capture by racing across state lines. FDR promoted a "New Deal for Crime," which, like his other New Deal policies, involved expanding the role of the federal government in serving the people.

Roosevelt’s original proposal for what would become the National Firearms Act of 1934, the first federal gun control law, sought to tax all firearms and establish a national registry of guns. When gun owners objected, Congress scaled down FDR’s proposal to allow only for a restrictive tax on machine guns and sawed-off shotguns, which were thought to be gangster weapons with no usefulness for self-defense.

Congress watered down FDR’s bill because of concerns about maintaining the right of people in rural communities, where there was little police presence, to have handguns for protection—not because of the Second Amendment. In congressional hearings into the NFA, Karl Frederick, the leader of the NRA, was called to testify. When asked if the Second Amendment imposed any limitations on what Congress could do in regulating guns, the NRA president’s reply was surprising: "I have not given it any study from that point of view."..