I would contend this is a civil rights and equal protection issue, well within the DOJ's purview. A better analogy than Barr being involved in a DUI would be if you were pulled over by a cop for having a Trump bumper sticker, charged with DUI with no evidence, denied legal counsel, and locked up and charged excessive bail.
This is a deprivation of rights, and by definition, a federal issue.
Either way, it is clear the fat-guy is practicing his bagpipes off in some corner.