A long-running legal battle over allegedly defective earplugs made by 3M arose after the company initiated a separate dispute against a smaller competitor, court documents showed.
3M’s effort to protect its military earplug business eventually led 3M to halt deliveries of one model of earplugs, and resulted in years of litigation, millions of dollars in costs and potentially billions in liabilities for the Minnesota-based manufacturing giant, according to court documents and company communications disclosed during the litigation. 3M said it was enforcing its patent rights in filing its suit against its competitor.