Existing law, the California Uniform Controlled Substances Act, categorizes controlled substances into 5 schedules and places the greatest restrictions on those substances contained in Schedule I. Existing law also defines drug paraphernalia and prohibits, among other things, the manufacture, sale, and possession, as specified, of drug paraphernalia. Existing law excludes from these prohibitions any testing equipment that is designed, marketed, used, or intended to be used to analyze a substance for the presence of fentanyl, ketamine, gamma hydroxybutyric acid, or any analog of fentanyl. This bill would additionally exclude from the definition of drug paraphernalia equipment, any equipment for testing a substance for the presence of contaminants, toxic substances, hazardous compounds, or other adulterants, as specified. The bill would exclude from the criminal liability of possessing drug paraphernalia those individuals obtaining controlled substance checking services and would state that it is lawful to use, possess, or distribute equipment intended for use or designed for use in identifying, or in analyzing the strength, effectiveness, or purity of a controlled substance. The bill would authorize specified entities to provide controlled substance checking services and would define those services as the process of identifying or analyzing a substance to determine its chemical composition. The bill would provide a person engaged in providing or using those services immunity from detention, arrest, criminal prosecution, and civil liability, among other things. The bill would require a controlled substance service provider, as defined, to destroy personally identifiable information from service users and would prohibit them from providing that information to law enforcement, as specified.