In May of 2024, the FDA issued a rule-challenging decision governing Laboratory Developed Tests (LDTs) as medical devices, subjecting them to stronger regulation. The move ends decades of enforcement discretion and establishes a three-tiered system of premarket approvals, quality system regulations, and surveillance for safety that all aim to improve diagnostic accuracy and patient safety. In plain language, this article describes why LDTs are crucial to health care in daily life and how new regulations aim to close important gaps in safety, making the tests used to decide life-altering choices both safe and responsible.