Justin Bieber Arrested

Justin Bieber just ratted on one of his drug suppliers to police -- telling cops, HIS MOM is the one who gave him the prescription medication he took shortly before his DUI arrest.

Law enforcement sources tell TMZ, cops grilled Bieber on what substances he had ingested before his arrest ... and the singer admitted he was under the influence of Rx meds, alcohol, and weed.

When asked what kind of Rx meds, we're told Bieber said anti-anxiety (such as Xanax) but he wasn't sure exactly what kind ... because he just takes whatever his mom Pattie gives him.

It's unclear if he has his own prescriptions for the drugs -- and his mom just handles them -- or if he's using his mom's prescriptions ... which would be illegal. If Bieber does have a valid prescription , the presence of the substance in his system probably won't be held against him.

As we reported, when police raided Bieber's house following the infamous egg attack, they found Xanax pills in the home ... so it all syncs up.

As we reported, Bieber also allegedly had a blood alcohol level of .04 ... and that will definitely come back to bite him in the ass.

We've reached out to Bieber's mom ... so far, no comment.

Seth Rogen has spoken ... calling Justin Bieber a "piece of sh*t."

Rogen posted the message on Twitter -- and it immediately blew up, with people retweeting the comment more than 10,000 times.

Rogen and Bieber have actually hung out together in the past -- most notably at the 2011 MTV Video Music Awards, where they seemed like they were getting along in a pretty chummy way.

Apparently, a lot can change in 3 years.

Justin Bieber made a point of showing off his tattoos and his muscles during his court appearance Thursday in Miami Beach.

Bieber appeared via closed circuit TV as the judge set bond in his DUI/resisting arrest/driving on a suspended license case.

Check out how Bieber rolled up his jumpsuit sleeves. He let his arms do the talking because he said nothing as the judge set bail at $2,500 ... which we're guessing he can afford.

It's not exactly a capital offense, but Bieber hired the best ... attorney Roy Black, who helped William Kennedy Smith beat the rape rap. He's also repped Rush Limbaugh and Kelsey Grammer.

Bieber was taken into custody and transported to the police department where his blood alcohol level was tested. Our law enforcement sources say Justin was given a field sobriety test at the scene ... and failed.

His was then taken to jail where he was booked and processed.

We're told Bieber had just left SET nightclub and was driving a yellow Lamborghini at the time cops spotted him in a residential neighborhood. Our sources say Justin's people actually blocked the street off so Bieber could drag race.

Sources say the person Justin was racing was also arrested. We're told that driver was Khalil, a well-known rapper on Def Jam Records. He was in a red Ferrari.

Justin had a passenger in the car -- Chantel Jeffries -- a model, who's dated multiple celebs including an NFL superstar.

The traffic stop was for drag racing and cops determined he was driving under the influence.

The photo (below) is Chantel -- the model who was in Justin's yellow Lambo -- and Justin. The pic was NOT taken at the time of the arrest.

Justin Bieber's gonna face the full wrath of the law after his arrest for DUI and drag racing ... so says the top dog in Miami Beach, Mayor Philip Levine.

Shortly after Justin's bust, Hizzoner was in Washington D.C. for a conference ... and told us folks in his city won't stand for Bieber or anyone else recklessly speeding while drinking and driving.

And if Bieber thinks he's gonna get special treatment while he's in custody -- the Mayor's got a strong opinion about that ... though he left a little wiggle room.

Justin Bieber's father helped facilitate the insanely stupid moves of his son that landed him in jail ... TMZ has learned.

Sources familiar with the situation tell us ... 38-year-old Jeremy Bieber was not only present when Justin was arrested early Thursday morning ... he was one of the people who helped block off the residential street so his son could drag race.

It's even worse ... Jeremy was in SET nightclub just before the arrest with Justin and was around him all day, when the self-confessed little pothead was smoking weed.

As we reported ... Justin admitted that he was under the influence of Rx drugs, alcohol and weed at the time of his arrest ... and Justin's dad was right there in the mix.

Unbelievable.