Sec. 4. (a) A person who causes serious bodily injury to another person when operating a vehicle:
(1) with an alcohol concentration equivalent to at least eight-hundredths (0.08) gram of alcohol per:
(A) one hundred (100) milliliters of the person's blood; or
(B) two hundred ten (210) liters of the person's breath;
(2) with a controlled substance listed in schedule I or II of IC 35-48-2 or its metabolite in the person's blood; or
(3) while intoxicated;
commits a Level 5 felony. However, the offense is a Level 4 felony if the person has a previous conviction of operating while intoxicated within the five (5) years preceding the commission of the offense.
(b) A person who violates subsection (a) commits a separate offense for each person whose serious bodily injury is caused by the violation of subsection (a).
(c) It is a defense under subsection (a)(2) that the accused person consumed the controlled substance in accordance with a valid prescription or order of a practitioner (as defined in IC 35-48-1.1) who acted in the course of the practitioner's professional practice.