The U.S. Supreme Court case National Labor Relations Board v. International Longshoremen's Association, AFL-CIO et al., 1979 revolved around the issue of whether a union could be held liable for secondary boycotts under Section 8(b)(4) of the National Labor Relations Act (NLRA). The International Longshoremen's Association had engaged in work stoppages to pressure neutral employers into ceasing business with companies that were involved in labor disputes with the union. The National Labor Relations Board argued this constituted an unlawful secondary boycott and sought enforcement orders against the union from federal courts, which was denied by both district and appellate courts on grounds that such actions did not fall within NLRA’s definition of “labor dispute”. However, upon reaching the Supreme Court, it reversed these decisions ruling that such conduct indeed violated Section 8(b)(4) as they coerced neutral parties and disrupted commerce; hence unions can be held accountable for secondary boycotts even if their primary dispute is with another employer.

In the dissenting opinion for the case of NATIONAL LABOR RELATIONS BOARD v. INTERNATIONAL LONGSHOREMEN'S ASSN., AFL-CIO, et al., Justice William Rehnquist argued that the majority's decision to uphold a National Labor Relations Board (NLRB) ruling against secondary boycotts was an overreach of judicial power and misinterpretation of labor law. He contended that Congress did not intend to prohibit all forms of secondary pressure when it enacted amendments to the National Labor Relations Act in 1959. Instead, he believed these laws were meant only to prevent unions from coercively involving neutral employers in their disputes with primary employers. In this particular case, he felt that there was no coercion involved as defined by Congress because there was no evidence showing any attempt by union members or officials to force shipping companies into ceasing business relations with foreign-flag vessels.