6 U.S.C. § 111 — Executive department; mission

(a) Establishment: the Department of Homeland Security is created as an executive department of the United States, the same kind of department described in title 5. (b) Mission: (1) in general, the Department's main job is to: (A) prevent terrorist attacks inside the United States; (B) reduce how vulnerable the United States is to terrorism; (C) minimize damage from terrorist attacks that do happen and help with recovery; (D) carry out all the duties of agencies moved into the Department, including watching for natural and human-made crises and planning for emergencies; (E) make sure that parts of the Department not directly about homeland security aren't cut back or ignored, unless Congress specifically says so; (F) make sure homeland-security efforts don't hurt the country's overall economic security; (G) make sure homeland-security efforts don't diminish people's civil rights and civil liberties; and (H) watch for links between illegal drug trafficking and terrorism, work to break those links, and help stop drug trafficking generally. (2) Responsibility for investigating and prosecuting terrorism: except where a law specifically gives this job to an agency moved into the Department, investigating and prosecuting terrorism remains the job of federal, state, and local law enforcement agencies that already have jurisdiction — not the Department itself.