Nurse practitioner prescriptive authority is governed by a complex intersection of federal law, state regulations, and professional ethics that varies significantly by jurisdiction. Understanding these frameworks is essential for safe, legal, and ethical prescribing practice. Prescriptive authority models exist on a spectrum. Full practice authority (FPA) states allow NPs to evaluate, diagnose, order diagnostics, and prescribe (including controlled substances) without physician oversight. Reduced practice authority states require a collaborative agreement with a physician. Restricted practice authority states require physician supervision for one or more elements of practice. The trend is toward FPA, with the National Academy of Medicine, the Federal Trade Commission, and the Veterans Health Administration all supporting removal of practice barriers. Controlled substance prescribing requires a DEA registration (Form 224) linked to the NP's state license. The Controlled Substances Act classifies drugs into five schedules: Schedule I (no accepted medical use -- heroin, LSD), Schedule II (high abuse potential with accepted medical use -- oxycodone, fentanyl, methylphenidate, amphetamines), Schedule III (moderate abuse potential -- buprenorphine, testosterone, ketamine), Schedule IV (low abuse potential -- benzodiazepines, zolpidem, tramadol), and Schedule...