Starbucks Pride Strike Highlights Murky Rules for Labor Walkouts

The union clash over Pride décor at Starbucks Corp. cafes poses a broader test on free speech in the workplace, with the coffee giant accusing labor leaders of illegally spreading misinformation to workers.

The dispute underscores how vague federal labor law is on whether workers can strike over social issues that aren’t directly related to their job duties. The question has become more urgent over the past several years as companies and individual workers speak out on Black rights, LGBTQ+ inclusion, sexual harassment, and other issues once considered off limits in corporate America.

Workers at about 150 Starbucks stores went ...