Evidence.
Positive Breathalyzer + alcoholic drinks present + minors = drinking underage.
If this went to trial and you saw that evidence, what else would you need to know?
So if one person is guilty - all 37 must be guilty too - great police state logic - guilty until proved innocent. All hail the death of liberty and the rise of the police state.
So next time you are at you favorite Red Neck bar and some Billy-Joe-Bob starts a fight - be prepared to go to jail - using your logic:
Bar + fight = everybody guilty
Or when you are driving home and Speed Racer beside you is clocked at 100MPH+ and you are ticketed (even though you weren't speeding) remember:
Car + Speeding = everybody nearby must be speeding.
Who needs evidence when the police can just use assumptions. Makes police work much easier and gives them more donut time.
You misunderstand the question. What would be your basis for seeking a breathalyzer test? The fact that a kid was there wouldn't be a basis for seeking the test.