Clinical laboratories in the United States are governed by a variety of required regulatory and optional accreditation bodies. All laboratories must comply with the federal Clinical Laboratory Improvement Amendments (CLIA) or state equivalents, while some laboratories choose additional accreditation partners. While not a regulatory body, International Standards Organization (ISO) is an internationally recognized quality system that includes best practices specific to clinical laboratories. Likewise, the Clinical Laboratory Standards Institute (CLSI) publishes guidance documents that include best practices for test validation. The Food and Drug Administration (FDA) has historically exercised enforcement discretion in regulating laboratory developed tests (LDTs), but that approach has changed with publication of the FDA's LDT final rule.