(a) A person who knowingly participates in the illegal drug market within this state is liable for civil damages as provided in this chapter. A person may recover damages under this chapter for injury resulting from an individual's use of an illegal drug.
(b) A law enforcement officer or agency, the state, or a person acting at the direction of a law enforcement officer or agency or the state, is not liable for participating in the illegal drug market, if the participation is in furtherance of an official investigation.