Back to cap. You blow 000 on a breathalyzer, you can't get a DUI. You're already arrested if you're blowing into a breathalyzer. So, that's cap. The officer might second-guess his decision to arrest you, but in order for you to be asked to take a breathalyzer, you have to already be under arrest for DUI. Now, can he un-arrest you and take you home? Sure, he could. I've seen it once or twice in my career, and it doesn't happen very often.