(a) while on duty, shall not use a controlled substance;

(b) while off duty, shall not use a controlled substance unless it is lawfully obtained, pursuant to a prescription, from a person authorized to dispense controlled substances;

(c) while on or off duty, shall not use any prescription drug whether or not it was lawfully obtained pursuant to a prescription, if the use of that drug would impair the skills, abilities or judgment of said person in discharging their responsibilities.

Controlled substance means any substance listed in Schedule I, II, III, IV or V of section 3306 of the Public Health Law. The misuse or abuse of prescription drugs shall not be an acceptable explanation for failing a drug test. Any person who violates this regulation, shall be immediately suspended from duty and, after review by the commissioners, may have their license or registration revoked.