Congress has the sole power to legislate for the United States. Under the nondelegation doctrine, Congress may not delegate its lawmaking responsibilities to any other agency. In this vein, the Supreme Court held in the 1998 case Clinton v. City of New York that Congress could not delegate a "line-item veto" to the President, by powers vested in the government by the Constitution.
Which doctrine says Congress can delegate its powers to whoever it wants?