Creates the First Responder Cannabis Testing Act. Provides that, before a first responder may be tested for any substance prohibited by the Cannabis Control Act, the person ordering the test must demonstrate there is cause for testing, such as an actual suspicion that the first responder is currently intoxicated with a substance prohibited under the Cannabis Control Act or there was vehicular crash or other accident at work that may have been caused by intoxication with a substance prohibited under the Cannabis Control Act. Provides that a test administered to detect any substance prohibited under the Cannabis Control Act shall be a saliva-based test and may not be a urine, blood, or hair follicle test. Provides that, if a first responder tests positive for any substance prohibited under the Cannabis Control Act, that first responder may be discharged only if there is evidence that the first responder was intoxicated with a substance prohibited under the Cannabis Control Act immediately prior to the start of or during the first responder's shift. Limits the concurrent exercise of home rule powers. Makes conforming changes in the Illinois State Police Act, the Compassionate Use of Medical Cannabis Program Act, and the Cannabis Regulation and Tax Act.