Medical Necessity
Whether a service is clinically warranted enough to be covered. In California and in Medicare Advantage, a licensed clinician has to make that call, not a tool.
Medical necessity is the coverage test that asks whether a service is clinically warranted for this patient, as distinct from whether the service exists in the benefit package. There is no single national definition. What counts is set by the plan contract, by program rules for public programs, and by whatever the applicable state or federal law says, which is why the same procedure can be necessary under one plan and reviewable under another.
It has become the sharpest line in health insurance AI because two governments drew it in nearly the same place. California’s Physicians Make Decisions Act says an artificial intelligence, algorithm, or other software tool “shall not deny, delay, or modify health care services based, in whole or in part, on medical necessity,” and that the determination may be made only by a licensed physician or a licensed health care professional competent to evaluate the specific clinical issues involved. Read the qualifier carefully. It is not a rule against relying on a tool alone; treating the model as one input among several does not satisfy it.
Medicare Advantage reaches a similar result through regulation rather than statute. A partly or fully adverse determination resting on medical necessity has to go in front of a qualified clinician before the plan issues it: a physician or comparably expert professional who knows the Medicare coverage criteria. In both regimes the compliance question is evidentiary rather than architectural: not whether a model was in the workflow, but whether the file shows which qualified person made the determination and on what clinical information. That is the same record prior authorization and utilization management depend on, and our health insurance map sorts it by program.