304 U.S. 333 (1938), Supreme Court of the United States
National Labor Relations Board v. Mackay Radio & Telegraph Co.
Under the NLRA, may an employer permanently replace employees who engage in an economic strike and thereafter refuse to discharge those replacements when the strike ends, and does an employer violate the Act by selectively refusing to reinstate certain strikers because of their union activity?
Although Section 13 of the NLRA protects the right to strike, an employer that has committed no unfair labor practice retains the right to continue its business during an economic strike by hiring permanent replacements for striking employees and is not required to discharge those replacements when strikers seek to return to work. However, Section 8(3) prohibits discrimination in terms or conditions of employment, including reinstatement decisions, intended to discourage union membership or penalize protected union activity. The NLRB's findings of fact are conclusive if supported by substantial evidence.
The Supreme Court held that Mackay lawfully could hire permanent replacements for economic strikers and was not obligated to discharge those replacements after the strike ended. However, the Court also held that substantial evidence supported the NLRB's finding that Mackay unlawfully discriminated against certain strikers because of their union activity, in violation of Section 8(3). The Court enforced the Board's order as to the discriminatory refusals to reinstate but refused to enforce the portion requiring displacement of permanent replacements to reinstate all strikers.
Mackay Radio established the enduring Mackay doctrine: employers facing an economic strike may hire permanent replacements and need not displace them when the strike ends. This doctrine has profoundly influenced bargaining dynamics by imposing a substantial risk on economic strikers. But Mackay also affirmed a key constraint: employers cannot selectively refuse to reinstate strikers or otherwise discriminate to discourage union activity. The decision thus draws a critical line between lawful operational continuity and unlawful anti-union discrimination. For law students, Mackay is a cornerstone of NLRA analysis. It frames the distinction between economic and unfair labor practice strikes and informs modern reinstatement rules later developed in cases such as NLRB v. Fleetwood Trailer Co. and NLRB v. Laidlaw Corp. It also illustrates how the Supreme Court defers to the NLRB's factual findings under the substantial evidence standard, while policing the scope of the Board's remedies.