Bieber Toxicology Report Positive for Weed, Xanax

It's been a busy legal day for Justin Bieber.

RELATED: Bieber Arrested In Toronto

The Canadian pop star, 19, has pleaded not guilty to charges of DUI, resisting arrest without violence and driving with an expired license, according to The Associated Press.

The charges stem from an incident last week in Miami, Fla. in which police suspected, but did not charge, the singer of participating in an illegal street drag race with R&B crooner Khalil Amir Sharieff.

Bieber surrendered to police in Toronto on Wednesday, Jan. 29, in regards to an alleged assault involving a limousine driver, according to CBC News. He has since been released.

RELATED: Bieber Releases Confident Video

Later, Bieber's manager Scooter Braun tweeted:

UPDATE: According to the official Miami Beach Police DUI Test report, Bieber's alcohol breath test showed an alcohol reading of .014 at 5:37 a.m. on January 23 and .011 at 5:40 a.m. -- both under the .02 limit of Florida for a driver under the legal drinking age of 21. Bieber's attitude was described as "cocky," "insulting" and "talkative," while using profanity. When Bieber was told he "reeked of marijuana," the singer reportedly said that "we were smoking all night in the studio." He also reportedly gave the officer a difficult time when taking the breath test, allegedly forgetting "basic instructions" and not being able to "blow continuously for more than a couple of seconds."

He also allegedly admitted to taking medications for anxiety but didn't know what medications he's been prescribed. "Well my mom takes care of all that stuff for me," he allegedly told the officer.

Bieber's preliminary toxicology report was released Thursday, showing that he tested positive for THC -- the active ingredient in marijuana -- as well as Alprazolam, also known as Xanax.