When I was job shadowing with an attorney, one guy in court who was at sentencing for his DUI had blown somewhere above .4, I can't remember exactly what it was. But it was enough to catch the judge off guard and ask him to repeat himself. Afterwords he said it was the highest he had ever had in his courtroom.
I think anything past .30 and they should be released and not charged for anything, just on the basis that they shouldn't have the cognitive ability to process any decisions at all, big or small, in that state.
"Got to love the Rhode Island Staties. They nail the guy for a .489 breathalyzer test, realize they are may be on the verge of setting a world record, so they tee him up again and like a true champion Stanley delivers with a .491 on the second try."