Investigators bring Cesar Sayoc's car to an FBI facility in Miramar, Florida.Johnny Louis / Getty

Donald Trump condemned a spate of attempted mail bombings this week as “terrorizing acts.” And his Justice Department today charged a suspect with five federal crimes, including interstate transportation of an explosive and threats against former presidents.

Announcing the charges against Cesar Sayoc of Florida, Attorney General Jeff Sessions characterized the mailings, which were directed at prominent critics of Trump, as “political violence”—which is a common way of describing terrorism.

So why wasn’t Sayoc charged with terrorism?

There’s a popular perception that investigators are quicker to label violent crimes by Muslims “terrorism” than they are, say, right-wing extremist violence. This perception is well founded, and the approach is morally inconsistent, but the reasons aren’t necessarily related to racism.

In the United States, the most frequently used terrorism-related charge, by far, is for providing “material support” to a foreign terrorist organization. Support can mean anything from offering money or advice to showing up in person to help a group that is on the State Department’s designated list of terrorist organizations.

These days, the organization at issue tends to be ISIS, though the same charge could also theoretically apply to offering support to the Japanese cult Aum Shinrikyo, which carried out a deadly sarin attack on the Tokyo subway in 1995, killing 13 people.

Modern terrorism in the United States is largely a homegrown phenomenon; even most of the actors charged with ISIS-related offenses in the U.S. are American citizens or permanent residents. But in the eyes of the law, the connection to an international terrorist group, even if it’s only rhetorical or ideological, matters a great deal.

For domestic actors without such connections, the law—and the intelligence community’s investigative powers—runs up against First Amendment and other civil-liberties protections. The U.S. government does not formally designate domestic terrorist organizations. So it may not be illegal to give money to a domestic extremist group like Aryan Nations, even if some members commit violence.

“The First Amendment protects the right of people to associate with each other,” said Mary McCord, a former acting assistant attorney general for national security at the Justice Department who is currently a professor at Georgetown Law. “And it certainly protects the right for people to express their points of view, political or otherwise.”

“We don’t worry about that with foreign terrorist organizations because foreign terrorist organizations don’t have First Amendment rights under the U.S. Constitution,” McCord said.

What about once an attack has been committed? Sayoc has not been charged with the federal crime of domestic terrorism, because there is no such federal crime. But domestic terrorists can still face severe penalties.

Timothy McVeigh killed 168 people in the Oklahoma City bombing, which is still the second-deadliest terrorist attack in U.S. history after September 11. McVeigh was tried in federal court, since there were eight federal agents among the dead; he received the death penalty.

Nor is it only terrorists without apparent connections to international groups who get charged with offenses other than terrorism. Nidal Malik Hasan killed 13 people in Fort Hood in 2009; he was an American citizen who had professed sympathy for the Taliban and tried to communicate with the radical cleric Anwar al-Awlaki. He was also tried on murder charges.

In effect, whether a suspect gets formal “terrorism” charges or not, the justice system still allows for harsh punishment. Sessions noted that if convicted, Sayoc could face up to 50 years in prison. But the political discussion remains acute and divisive.

“Often the question really is one that focuses just on the policy side, whether or not we want to think of this as terrorism, or whether it feels like terrorism,” said Matthew Olsen, the former head of the National Counterterrorism Center, which coordinates terrorism-related intelligence across the government.

Either way, with the count of mailed explosive devices now at 13 and a suspect in custody, the terror has spread, and so have the politics.

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