Justin Bieber pleaded not guilty to DUI and drag racing after last week's arrest in Miami, and while he only had weed and Xanax in his system, cops maintain that he was cocky, agitated and rude when dealing with them.

Arrest report docs claim that he was many things, among them "excited, talkative, insulting, cocky."

One police officer said the singer "reeked of marijuana," which has a very distinct, somewhat sweet smell. The Biebs reacted by saying, "We were smoking all night at the studio."

At first, Bieber seemed OK with submitting to a breath test, but changed his mind and asked about his license if he refused. Authorities claim he was in such a state that he couldn't follow their simple instructions about how to provide the sample.

The report states that the singer "had extreme difficulty providing a continuous breath." It made cops think he was purposefully trying to mess up his test with improper blowing. That's when he became agitated and claimed he was "blowing into the hose like he blows into his trumpet." Whatever that means...

His BAC was .014, which is not much. His toxicology report is here. But he failed the field sobriety test since he was off balance, swaying, couldn't follow a moving object smoothly and couldn't touch his finger to his nose while closing his eyes.