The officer used his discretion in doing the logical thing and getting his friends to pick him up. Yes, he could have arrested him for DUI but it would have been easily thrown out because there were no "wheel" witnesses to him actually driving the car. He was out and hugging a tree when you saw him and when the officer saw him.
And even if the kid in his drunken state actually admitted to the officer he was driving, any defense attorney would have had a fun time with that. It would go something like this: (with a nod to Blazing Saddles)
Lawyer: So officer, according to your testimony my client was obviously intoxicated right?
Officer: Yes Sir, he was.
Lawyer: His speech was slurred and incomprehensible, right?
Officer: Yes it was.
Lawyer: Pretty much gibberish right?
Officer: Yes.
Lawyer: Authentic Frontier Gibberish?
Officer: Absolutely
Lawyer: Officer, are you a certifed interpreter of Authentic Frontier Gibberish?
Officer: Well no I'm not but..
Lawyer: So you have no idea what my client Mr. Gabby Johnson actually said, yet you claim he admitted to driving that car and parking it by the side of the road. And as you yourself testified earlier, you never did actually see him in the car did you...or behind the wheel did you?
Officer: No, I didnt.
Lawyer: No more questions for this witness, your Honor. Your Honor, motion for directed verdict of not guilty for failing to show a required element of the crime. There were no witnesses to my client being behind the wheel of the car.
Judge: Motion for directed verdict of Not Guilty is granted.
:-)
I was a former prosecutor decades ago and actually had a trial go just like this: the guy had come to his senses in the bar parking lot before leaving and got out of his car and was found snoring in the grass twenty feet from the car. The officer took the guy's wallet out and matched his driver's license name with the registration of the car and arrested him for a DUI. It only took five minutes for the not guilty verdict by a jury who all believed he did exactly the right thing by sleeping it off in the poison ivy bushes.
https://www.youtube.com/watch?v=ke5M...=MichaelTurner