40 U.S.C. § 3113

An officer of the Federal Government authorized to acquire real estate for the erection of a public building or for other public uses may acquire the real estate for the Government by condemnation, under judicial process, when the officer believes that it is necessary or advantageous to the Government to do so. The Attorney General, on application of the officer, shall have condemnation proceedings begun within 30 days from receipt of the application at the Department of Justice.