When Metropolitan Edison Co. (defendant) began constructing the Three Mile Island nuclear power plant in 1968, it entered a collective-bargaining agreement (CBA) with the International Brotherhood of Electrical Workers (IBEW) with a no-strike clause. Union members nonetheless stopped work four times from 1970 to 1974. Each time, the company disciplined union stewards more severely than it disciplined other workers who participated. IBEW filed two grievances, but the arbitrator found the stewards breached an affirmative duty to uphold the CBA that justified more severe sanctions. In 1977, another union set up a picket line at the construction site entrance, and IBEW members refused to cross it. The company told the local IBEW president he had a duty to ensure compliance with the no-strike provision by crossing the picket line himself and inducing others to follow, but he refused. Instead, after about four hours, the two unions negotiated a settlement that required a second plant entrance. The company suspended workers who refused to cross the picket line for five to 10 days but suspended the IBEW president and vice-president for 25 days, claiming the refusal to end the strike by crossing the picket line warranted additional suspension. IBEW filed unfair-labor-practice charges, and the National Labor Relations Board (NLRB) (plaintiff) found that penalizing the union officials violated the National Labor Relations Act (NLRA). The appellate court affirmed, and the Supreme Court accepted review.