@EqualityFLSTPete,
I don't think we should assume there was a previous DUI charge, unless someone knows that for a fact.
Swift is in enough trouble, he doesn't need people spreading rumors about him, if that previous DUI arrest is only a rumor.
I can believe he was a habitual heavy drinker, who might have routinely driven while impaired, because that seems to be the case with most people who wind up facing a DUI manslaughter charge--eventually, their luck runs out.