Employment Litigation · Primary-source case analysis

Mackay Radio: Economic Strikers Could Be Replaced, but Not Discriminated Against for Union Activity

By Aneeta Mishra and Timothy Chan

Published August 20, 2026 · Updated October 20, 2026

Decision: NLRB v. Mackay Radio & Telegraph Co., 304 U.S. 333 (1938).

An employer’s ability to retain strike replacements did not permit it to select returning workers for exclusion because they led the union. In NLRB v. Mackay Radio & Telegraph Co., 304 U.S. 333 (1938), the Supreme Court sustained the Board’s finding that a reinstatement process discriminated against five active union members. On May 16, 1938, it reversed the Ninth Circuit’s refusal to enforce the order and remanded. The actual list, return instructions and treatment of other strikers explain why the employer’s vacancy explanation failed. Mackay Radio, pages 345–348, 351.

Eleven strikers were singled out for an extra application step

The company operated a San Francisco communications office. Negotiations over wages and working conditions had not produced an agreement, and its employees joined a strike beginning October 4, 1935. To maintain service, the company brought workers from other offices. By October 7, some strikers wanted to return. Management said they could come back together, subject to keeping the replacements who wanted to remain in San Francisco. Mackay Radio, pages 336–338.

A supervisor marked eleven names on the striker list and said those workers needed applications approved by an executive in New York. That instruction also affected who was notified of the return meeting. Most strikers resumed work on October 8. Six of the eleven singled-out workers also returned without waiting for that special approval. The other five, prominent in union and strike activity, were told the workforce was full and they would have to wait for vacancies. Only five replacements ultimately chose to stay. Mackay Radio, pages 338–339, 346–347.

The Board found unlawful discrimination and ordered reinstatement and make-whole relief for the five. The Ninth Circuit refused enforcement, with differing statutory and constitutional rationales among its judges. The Supreme Court reviewed those objections as well as the evidence supporting the Board’s order. Mackay Radio, pages 340–343.

A labor dispute preserved employee status

The company argued that the record did not establish the labor dispute needed for continued employee status. The Court distinguished a dispute over bargaining terms from an employer’s unfair labor practice. The pending negotiations and strike over their unsatisfactory progress established the former even though the record showed no employer unfair labor practice before the strike. The Board did not need to use a particular formula in its findings or decide that the union’s negotiating assessment was wise. Mackay Radio, pages 344–345.

Section 2(3) included workers whose work ceased because of or in connection with a current labor dispute, subject to the statutory terms. These strikers therefore remained employees protected against discrimination. At the same time, the Court recognized the employer’s right to continue its business with replacements and to retain those hired into the vacant positions. Employee status and an immediate right to displace a replacement were separate questions. Mackay Radio, pages 345–346.

The selection evidence defeated the asserted vacancy explanation

The decisive question was why these five were excluded. The Board credited evidence that several were told their union activity made them undesirable. Some delayed returning because they understood management required advance approval, only to be told afterward that the quota was full. Meanwhile, six people on the same special list had been allowed back without that approval. Those inconsistent instructions and comparisons supported the finding that late application was an afterthought rather than the true reason. Mackay Radio, pages 346–347.

The Court did not choose between competing witnesses anew. It found evidence supporting the Board’s determination that the company used its list and reinstatement process to discriminate against the most active union members. The company’s lawful replacement interest did not explain that discriminatory selection. Mackay Radio, page 347.

The remedy addressed the discrimination actually found

The Court upheld reinstatement to the five workers’ former positions and compensation for losses caused by the discrimination. Backpay had to credit earnings through reinstatement. The notice obligation was read with the order’s prohibition on union-based discrimination, rather than as a promise of discharge immunity. The Court also rejected the employer’s constitutional objection to continued employee status. Mackay Radio, pages 347–348.

The employer separately complained that changes between discharge and refusal-to-reemploy language denied it a fair hearing. The Court found that everyone understood the actual discrimination claim and that the employer had a full opportunity to defend its conduct. On that record, the absence of the trial examiner’s usual intermediate report did not require setting aside the order. The judgment was reversed and the case returned to the appellate court for proceedings consistent with the opinion. Mackay Radio, pages 349–351.

For a current dispute, the NLRB’s strike-rights guide distinguishes economic strikers from unfair-labor-practice strikers. It explains that bona fide permanent replacements can delay economic strikers’ immediate reinstatement, while qualified returning workers may retain recall rights after an unconditional request. Unfair-labor-practice strikers have different reinstatement protection. The guide also identifies limits involving purpose, timing and serious misconduct. That current classification work belongs alongside—not inside an overbroad paraphrase of—the 1938 holding.

Preserve the return instructions and selection record

The useful comparison is between what workers were told and how those instructions were applied. Keep the return-to-work request, any applications or approval requirements, the replacement terms, vacancy information and communications explaining who was accepted or excluded. Mackay Radio turned on evidence that the supposedly neutral process treated active union members differently. Our Transportation Management analysis addresses a different NLRA question: Whether lawful discipline would have occurred without organizing activity.