Sec. 20. (a) Except as provided in section 30 of this chapter, a prescription or drug order for a legend drug is not valid unless the prescription or drug order is issued for a legitimate medical purpose by a practitioner acting in the usual course of the practitioner's business. (b) A practitioner may not knowingly issue an invalid prescription or drug order for a legend drug. (c) A pharmacist may not knowingly fill an invalid prescription or drug order for a legend drug. [Pre-1993 Recodification Citation: 16-6-8-3.5.] As added by P.L.2-1993, SEC.25. Amended by P.L.48-2015, SEC.2.