Civil law governs relations between individuals and organizations, and is used when a wrongful act is committed against another person. Criminal law governs relations between individuals and the government, and is used when a wrongful act harms society. The Controlled Substances Act classifies drugs into five schedules based on their potential for abuse and addiction, from Schedule I which has no accepted medical use to Schedule V which has a limited addiction potential. Prescriptions must be issued and signed only by the registered health professional. A subpoena is a court order that can demand a person or medical records, while an expert witness testifies in court about the standard of care in a particular medical field.