Ind. Code § 22-9-5-12

Sec. 12. As used in this chapter, "illegal use of drugs" means the use of drugs the possession or distribution of which is unlawful under the Controlled Substances Act. The term does not include the use of a drug taken under the supervision of a licensed health care professional, other uses authorized by the Controlled Substances Act (21 U.S.C. 812), or other provisions of federal law.