You can argue all day.Bottom line is, its judgement call that the pigs get to make.My best buddy failed one before.He neither drinks or smokes or pops pills.Notta.He was just with me so the pig nailed him.After paying the lawyer charges were dismissed,but he got charged w/ a DUI.Lost his license while it went to court and it stayed on his record.His record doesn't mention dismissed anywhere.
You are correct, it comes down to the cops judgement, for better or worse. Your friend should get his DUI removed from his record. It takes some time, but worth it.
The new zero tolerance laws are insane, look how many people get dui's in winter while sleeping in the vehicle while running so the heater works. Or they have the keys in their pocket. Laws that try to prove a persons intent, even without any evidence, do nothing from what I saw over the years. Minus create funding for some group.
In AK your rights change with a lawyer, but you must have the lawyers contact card to hand over at the time of the stop.