<P> The amendments also authorized individual states to outlaw union security clauses (such as the union shop) entirely in their jurisdictions by passing right - to - work laws . A right - to - work law, under Section 14B of Taft--Hartley, prevents unions from negotiating contracts or legally binding documents requiring companies to fire workers who refuse to join the union . Currently all of the states in the Deep South and a number of states in the Midwest, Great Plains, and Rocky Mountains regions have right - to - work laws (with six states--Alabama, Arizona, Arkansas, Florida, Mississippi, and Oklahoma--going one step further and enshrining right - to - work laws in their states' constitutions). </P> <P> The amendments required unions and employers to give 80 days' notice to each other and to certain state and federal mediation bodies before they may undertake strikes or other forms of economic action in pursuit of a new collective bargaining agreement; it did not, on the other hand, impose any "cooling - off period" after a contract expired . The Act also authorized the President to intervene in strikes or potential strikes that create a national emergency, a reaction to the national coal miners' strikes called by the United Mine Workers of America in the 1940s . Presidents have used that power less and less frequently in each succeeding decade . President George W. Bush invoked the law in connection with the employer lockout of the International Longshore and Warehouse Union during negotiations with West Coast shipping and stevedoring companies in 2002 . </P> <P> The Act also prohibited federal employees from striking . </P> <P> The amendments required union leaders to file affidavits with the United States Department of Labor declaring that they were not supporters of the Communist Party and had no relationship with any organization seeking the "overthrow of the United States government by force or by any illegal or unconstitutional means" as a condition to participating in NLRB proceedings . Just over a year after Taft--Hartley passed, 81,000 union officers from nearly 120 unions had filed the required affidavits . In 1965, The Supreme Court held that this provision was an unconstitutional bill of attainder . </P>

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