Hair Follicle Drug Tests Explained: What Courts Can and Can’t Do. In this video, we break down a common misconception about hair follicle drug testing—what it actually measures, how far back it can detect substances, and what courts can and cannot legally require. Many people believe judges can order hair follicle tests, but that’s not always the case. While individuals can agree or stipulate to this type of testing, it’s important to understand the legal and clinical distinctions between hair t