(Bloomberg) -- With the future of the US telehealth industry at stake, Bart Stupak, a former congressman and current lobbyist, has spent the past year trying to undo legislation he helped pass more than a decade ago. Stupak is asking federal policymakers to let online clinicians keep prescribing controlled substances — even though federal investigators are looking at that practice and have interviewed former employees at two telehealth startups, according to people familiar with the conversations.