The Clinical Laboratory Improvement Amendments of 1988 (CLIA) require any U.S. facility that examines human specimens for diagnostic purposes to hold a CLIA certificate from the Centers for Medicare & Medicaid Services (CMS). Tests are categorized by complexity (waived, moderate, high), and a Certificate of Waiver — the most common CLIA certificate for occupational-health clinics — authorizes only FDA-cleared waived tests. Waived tests are defined by statute as "simple laboratory examinations and procedures that have an insignificant risk of an erroneous result." Typical waived tests used in occupational medicine include urine dipstick, blood glucose, urine hCG (pregnancy), rapid strep, and many instant point-of-care drug screens. Performing any test outside the waived category (e.g., laboratory-based drug screen confirmation, microscopy, blood chemistry panels) requires a Certificate of Compliance or Accreditation — which adds personnel, quality control, and proficiency-testing requirements. CLIA scope is one of the most consequential operational decisions for an occ-med clinic: it determines what can be done in-house vs. sent to a reference lab.