"Our analysis of the characteristics of the 48 Good Samaritan laws found that they differ in the protections they offer to individuals who call for medical assistance for an overdose victim. First, there is variation in whether criminal immunity—an exemption from prosecution—is offered and, if so, for which type of drug offense, such as possessing or delivering drugs in violation of an otherwise applicable drug law. Second, there is variation in when criminal immunity takes effect—the timing can be before an individual would otherwise be arrested and charged as a criminal defendant or after these events but before an individual is prosecuted.
"Finally, because a jurisdiction retains the power to prosecute individuals who do not have criminal immunity, some Good Samaritan laws offer either an affirmative defense at trial or a mitigating factor at sentencing, or both."
"Most States Have Good Samaritan Laws and Research Indicates They May Have Positive Effects," US General Accountability Office, March 2021, GAO-21-248.