A U.S. district court struck down the FDA’s final rule to regulate lab‑developed tests (LDTs), a ruling that marked the dominant regulatory story of 2025. Legal challenges argued the rule exceeded FDA authority; the court agreed, leaving major regulatory uncertainty for diagnostics manufacturers and clinical labs. The decision halted the agency’s plan to bring LDTs under premarket and quality requirements and has broad implications for oversight of next‑generation sequencing and other in‑house tests. Attempts to regulate AI in diagnostics also featured prominently in 2025’s regulatory landscape. Stakeholders across diagnostics, clinical labs and health systems will need to reassess compliance strategies while following potential appeals and future rulemaking.