grand jury

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A jury convened to determine if there is sufficient evidence to warrant the indictment of a suspected offender. A federal grand jury consists of between 16 and 23 persons and is required by the Fifth Amendment to the US Constitution before a person can be indicted for a serious criminal offense under federal law.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun law A group of citizens assembled by the government to hear evidence against an accused, and determine whether an indictment for a crime should be brought.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a jury to inquire into accusations of crime and to evaluate the grounds for indictments