During his 16 years in the U.S. House of Representatives serving Rhode Island's First Congressional District, Kennedy led a surge in support for mental health equity, becoming one of the most recognized advocates for the cause in Congress. He is most widely known as the lead sponsor of the groundbreaking Mental Health Parity and Addiction Equity Act of 2008 (The Federal Parity Law), which requires insurers to cover treatment for mental health and substance use disorders no more restrictively than treatment for illnesses of the body, such as diabetes and cancer.