10. a. An action by an individual user of a controlled dangerous substance is governed by the principles of comparative responsibility. Comparative responsibility attributed to an individual user does not bar the user's recovery but diminishes the award of damages proportionately, according to the measure of responsibility attributed to the user. The burden of proving comparative responsibility is on the defendant, who shall prove comparative responsibility by clear and convincing evidence.
b. Comparative responsibility shall not be attributed to a plaintiff who is not an individual user of a controlled substance, unless that plaintiff knowingly gave the individual user money for the purchase of the controlled dangerous substance.