Section 105(c) of the federal Mine Safety and Health Act (30 U.S.C. § 815(c)) prohibits an employer from taking adverse action against an employee “because of” the employee’s reporting a violation of the Act or seeking benefits under it.  Following the Supreme Court’s decisions in Bostock v. Clayton Cnty., 140 S.Ct. 1731, 1739 (2020) and other recent cases, this decision holds that when Congress uses “because” unmodified by preceding or subsequent adjectives, it means to incorporate a traditional “but for” standard of causation.  The “but for” standard requires only that the prohibited motive be a substantial factor in causing the adverse action; it need not be the sole cause.  So the defendant cannot escape liability merely by showing that another cause or motive also contributed to the challenged employment decision.