With applied behavior analysis (ABA) joining the mainstream of medically necessary treatments, insurers and managed care organizations have moved to introduce policies intended to influence treatment decisions – critical decisions about how many hours of ABA are medically necessary, which locations are allowable, and who must participate in treatment. Arbitrary policies that constrain behavior analysts from designing and implementing the most effective treatment plan are often indicative of an overreach by the funding source. With no statutory definition of medical necessity governing commercial insurance, behavior analysts are in a position to shape funding practices by understanding the laws and regulations that underpin patient rights in the determination of medically necessary treatment. This presentation seeks to empower behavior analysts to challenge improper policies, stand by their clinical recommendations, and ensure that behavior analysts – not funding sources – set the standard of care for ABA.