Read: If the pipe bomb mailings aren’t terrorism, what is?

The Oklahoma City bomber, Timothy McVeigh, was convicted of murder, and the Charleston church shooter, Dylann Roof, was convicted of federal hate crimes, despite the fact that both men’s actions clearly met the U.S. definition of terrorism. Ted Kaczynski, a.k.a. the Unabomber—one of the most famous American terrorists, who earned his sobriquet sending bombs through the mail—pleaded guilty to illegally transporting, mailing, and using bombs, and to three counts of murder, but not to terrorism. And now the suspect responsible for the recent spate of mail bombs is unlikely to be charged with terrorism. But if he’d waved an ISIS flag instead of a MAGA hat, the story would be quite different.

The same violent crime is labeled and tried differently depending on what inspired it. This may seem like semantics, and thus inconsequential, but the terrorism label matters in part because it carries a powerful stigma. Describing domestic terrorists as terrorists can help to discredit them among potential supporters and isolate them from the wider public.

The United States has devoted immense resources to combating jihadist ideology over the past 17 years. Soon after 9/11, the newly appointed U.S. ambassador to Saudi Arabia pressed the government there to rein in the religious establishment from promoting the radical Wahhabi doctrine that inspires many jihadists. “What you teach in your schools and preach in your mosques now is not an internal matter,” the ambassador told his Saudi counterparts. “It affects our national security.” Many homegrown terrorists are inspired by foreign jihadist ideology, but others are inspired by U.S. extremist movements. The government has not made a similar effort to hold this latter set of actors accountable.

Instead, the federal government has kneecapped itself when it comes to fighting domestic terrorism. Designating foreign groups as terrorist organizations enables prosecutors to charge individuals with providing material support to them. Stateside, because there are no such designations, it is more difficult to curb financing or other forms of support for violent extremist organizations.

Read: The difference between a killer and a terrorist

Some individual states have domestic terrorism laws in place, but this patchwork system is no substitute for a comprehensive federal law. It’s also not terribly useful in cases where the crime in question crosses state boundaries or touches on federal agencies, such as the U.S. Postal Service.

The administration and Congress need to work together to amend the law in order to give the criminal charge of domestic terrorism some teeth. Beyond the immediate benefits in terms of administering justice, this move could also force the federal government to clarify its concept of domestic terrorism as a first step toward developing a list of designated individuals or organizations.