Jeff Sessions asked Congress to repeal a 2014 law prohibiting the DOJ from using federal funds to prosecute marijuana violations that are legal under state medical-marijuana laws. He argued that this step was necessary because of the "historic drug epidemic," which involves opiates, not marijuana (WaPo).
Pennsylvania Governor Tom Wolf wrote a letter urging the Trump administration to avoid interfering with the state’s medical marijuana program and threatening legal action in the event of attempted interference (Penn Live).