“In the U.S., more people are killed by far-right extremists...

“In the U.S., more people are killed by far-right extremists than by those who are adherents to Islamist extremism,” said Mary McCord, a Georgetown University law professor and a former senior Justice Department official for national security. Her comments came at a discussion last week at the 9/11 Memorial and Museum, which commemorates victims of the most notorious attack by international terrorists on American soil.

Even as the menace from homegrown extremists grows more explicit, however, law enforcement is wrestling with how to combat it. That challenge has spawned a fervent debate over whether the United States needs a new law to specifically criminalize domestic terrorism, or whether such a statute would threaten basic First Amendment rights.

Proponents argue that a domestic terrorism law would streamline and clarify the patchwork of charges now used against homegrown extremists, charges that often avoid even mentioning terrorism.

Opponents counter that a new law would amount to a worrisome expansion of government powers, and might face constitutional challenges on the grounds of impinging on free speech.