The FAA medical form asks you to list any non traffic felony or misdemeanor convictions along with a separate block for DWIs. To work at a major airport, TSA requires a background check that goes back 10 years and includes felony drug convictions. You can get a Sport Pilot certificate without a medical but it just lets you fly two seat aircraft during the day. As someone said, open the phone book, US gov, Dept. of Transportation, FAA, Flight Standards District Office. There's one in most large cities. They're the ones who are going to give you the certificate, ask to talk with an Safety Inspector.