The Fort Hood soldier charged with 13 counts of premeditated murder in the 2009 military post rampage cannot plead guilty, a judge ruled Wednesday.

The Associated Press reports that Maj. Nidal Hasan’s attorneys said he wanted to plead guilty. He’s barred, however, by Army rules. Military judges can’t take guilty pleas from defendants who face the death penalty, AP says. So attorneys tried to get the judge to accept a guilty plea for 13 counts of unpremeditated murder — to no avail, AP reports.