That can be found in the 5th Amendment

The U.S. Department of Justice has filed a criminal complaint against Boston Marathon bombing suspect Dzhokhar Tsarnaev... The criminal complaint was filed in Boston federal court, meaning the Obama administration decided to use the civilian court system rather than turn Mr. Tsarnaev over to the military for prosecution.

Funny, that's such an easy call for everyone except the ignorant, phony-conservative, 'constitutionalists'.