The main purpose of the legislation known as the "Stop Pills That Kill Act" is to strengthen regulations around fentanyl, its analogues, and counterfeit substances that resemble these drugs. The goal is to combat the rising dangers associated with these substances, which have been linked to a significant number of overdose deaths. Key provisions of the Act include defining what constitutes counterfeit fentanyl or methamphetamine substances. This includes any substance that contains fentanyl or methamphetamine and is falsely marketed or labeled to look like another product.