The Taft-Hartley Act was a major anti-union bill that is regarded as one of the main reasons for the decline of the US labor movement. It's repeal has been a major goal of the US labor movement, with various politicians occasionally taking up the cause, but to date the law remains in effect.
What is a likely scenario to get the Act repealed, whether through Congress or the Supreme Court striking it down? The scenario has to take place after the act was passed, so having Truman's veto not get overruled doesn't count.