The United States Department of Justice (DOJ) is a Cabinet department in the United States government designed to enforce the law and defend the interests of the United States according to the law and to ensure fair and impartial administration of justice for all Americans (see 28 U.S.C. § 501). The DOJ is administered by the United States Attorney General (see 28 U.S.C. § 503), one of the original members of the cabinet.

The Attorney General was initially a one-person, part-time job, established by the Judiciary Act of 1789, but this grew with the bureaucracy. At one time the Attorney General gave legal advice to the U.S. Congress as well as the President, but this had stopped by 1819 on account of the workload involved.

In 1867, the U.S. House Committee on the Judiciary, led by Congressman William Lawrence, conducted an inquiry into the creation of a "law department" headed by the Attorney General and composed of the various department solicitors and United States Attorneys. On February 19, 1868, Lawrence introduced a bill in Congress to create the Department of Justice. This first bill was unsuccessful, however, as Lawrence could not devote enough time to ensure its passage owing to his occupation with the impeachment of President Andrew Johnson.