In that same year he joined the Philadelphia VA Medical Center where he is currently the interim medical director for the Opioid Treatment Program. He has been active in the research and treatment of substance use disorders. He has been the principal investigator for numerous clinical trials at both Penn and the VA involving pharmacologic treatments for alcohol, cocaine and opioid dependence. For the past 10 years he has focused research on the treatment of opioid addicted persons in the criminal justice system. Dr. Cornish taught addiction treatment and psychopharmacotherapy to medical students, nurses, residents, fellows, social workers and criminal justice professionals. He has trained several addiction fellows who have developed outstanding academic careers. He also taught health care students as a visiting professor at the Université de Bordeaux (France).