Anti-Moonlighting clauses are perfectly legal, though not without controversy: https://www.shrm.org/resourcesandtools/legal-and-compliance/employment-law/pages

Anti-Moonlighting clauses are perfectly legal, though not without controversy: https://www.shrm.org/resourcesandtools/legal-and-compliance/employment-law/pages/moonlighting-ban-worded-too-broadly.aspx https://www.shrm.org/resourcesandtools/legal-and-compliance/...