On the spot… after a trial… whatever. I don’t think a 5% reduction is worth taking the step of granting a police officer with a tube the power of judge, jury, and executioner.
If we’re serious about curtailing drunk driving, let’s not revoke licenses at all, or at least without multiple warnings (unless death or injury results). Instead, we should reregister drunk drivers’ license plates so that they somehow convey the offense, perhaps with different colors or symbols related to the number of incidents — say, one red bottle for each. We could even go so far as to give police officers more discretion in pulling over drivers based on these plates.
I’ve heard that Ohio did something like that, once, but that it was abandoned after too many important people were seen driving around with their shiny new tags. That’s an outcome that would simply have to be resisted, but it does offer a different context for considering the on-the-spot revocation: I wonder whether the suddenness of the penalty, all within one traffic stop, mightn’t give police officers (who are human, after all) incentive not to test or to pull over “important people” in the first place.