What were some steps taken by employers to deter workers from joining the union?

Employers believed unions were bad for business, and many tried to stop them. For example, some employers required new workers to sign a "yellow-dog" contract, promising not to join unions. Employers also used spies who would tell managers of any union activities among workers. Workers who were sympathetic to unions often lost their jobs. U.S. courts of law got involved in some disputes. Judges issued orders to end strikes they viewed as a threat to property or as a violation of antitrust laws