A healthcare professional approving a drug for a condition for which it is not approved by the necessary regulatory body.

In the USA, the FDA approves a drug for prescription use, and continues to regulate the pharmaceutical industry. The FDA does not have the legal authority to regulate the practice of the medicine by professionals, and a physician may prescribe a drug off label.

In Europe the EMA (European Medicines Agency) provides protection and promotion of public and animal health, through the evaluation and supervision of medicines for human and veterinary use.

See also:
Prescription Medicines Code of Practice Authority (PMCPA)
Prescribing Analysis and Cost (PACT)
Food And Drug Administration (FDA)
European Medicines Agency