Quick search by citation:

45 U.S. Code § 231s - Separability

If any provision of this subchapter, or the application thereof to any person or circumstance, should be held invalid, the remainder of such subchapter, or the application of such provision to other persons or circumstances, shall not be affected thereby.

(Aug. 29, 1935, ch. 812, § 20, as restated June 24, 1937, ch. 382, pt. I, 50 Stat. 307, as restated Pub. L. 93–445, title I, § 101, Oct. 16, 1974, 88 Stat. 1351.)