Passed over Harry Truman's veto in June 1947, Taft–Hartley amended the Wagner Act by outlawing closed shops, secondary boycotts, and jurisdictional strikes; permitting states to enact 'right-to-work' laws banning union-security clauses; and authorizing the President to seek an 80-day injunction against strikes that imperil national health or safety. It also required union officers to file anti-communist affidavits (a provision later struck down). Truman called it the 'slave-labor bill'; organized labor has spent seventy-five years trying to repeal parts of it. Its permission of state right-to-work laws is the reason U.S. private-sector unionization varies dramatically by region.