In a letter to lawmakers Friday, the Department of Justice said just over 400 alleged terrorists have been tried in civilian courts since Sept. 11, 2001.

The letter, by Assistant Attorney General Ronald Weich and addressed to Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.) and ranking Republican Jeff Sessions of Alabama, is a response to Republicans who previously questioned the accuracy of statistics provided by the DOJ on the number of civilian terrorist trials.

The 400 cases took place between Sept. 11, 2001 and March 18 of this year, Weich said, and the department included only convictions in the tally, not cases that are still ongoing. The number also doesn’t include domestic terrorism cases, said Weich, who heads the Justice Department’s Office of Legislative Affairs.

The department also provided lawmakers with a chart detailing each case, according to The Washington Post’s blog The Plum Line.

In defending his decision last November to prosecute alleged Sept. 11 mastermind Khalid Sheikh Mohammed in New York federal court, Attorney General Eric Holder said that 300 alleged terrorists had been successfully prosecuted in civilian courts. Republicans quickly questioned that claim, and Sessions called the 300 number “unsubstantiated.”

UPDATED: In a sharply worded rebuttal issued Friday afternoon, Sessions again challenged the DOJ’s accounting of alleged terrorists tried in civilian courts. According to Sessions, the terrorists on the list were not high-value terrorists and their offenses were much less severe than the charges against KSM.

“It is simply disingenuous for the Attorney General to argue that these cases demonstrate that captured enemy combatants, as classified under the 2009 Military Commissions Act, are better tried in civilian rather than military court,” Sessions said in a statement.

Originally posted on Main Justice.