In the world of rap, he's known as Meek Mill, a 25-year-old North Philly street rapper with a growing reputation as the "next big thing."

Big enough that, according to Meek Mill's tentative calendar, he's supposed to be in Los Angeles on Wednesday to appear on the Conan O'Brien show, his last U.S. stop before ending 2012 in Africa with shows in Lagos, Nigeria, and Libreville, Gabon.

But to Philadelphia's criminal justice system, he's just Robert Williams, on probation for a 2008 gun-and-drug conviction for which he needs to periodically appear in Philadelphia courts. And, unless Common Pleas Court Judge Genece E. Brinkley says otherwise at a hearing Monday, Meek Mill's next tour will be limited to the streets of North Philadelphia.

"What's the reason for it when most people keep in touch by Skype?" asked Center City criminal defense lawyer Dennis Cogan, who said he believed Williams was being targeted because of his celebrity status.

On Wednesday, Cogan and associates Gary S. Silver and Susan V. Buck filed a motion asking Brinkley to lift any ban on Williams' travel for concert and other related appearances.

The motion contends the travel ban "could potentially cost [Williams] approximately $500,000 in estimated revenue over the course of the next three weeks and significant loss of momentum in his emerging career."

The motion includes page after page of e-mails that Cogan said informed the court in advance and documented every moment Williams was out of the city.

Assistant District Attorney Noel A. DeSantis said she would oppose reinstating Williams' travel permit.

"In my opinion, as representative of the commonwealth, he needs to be becoming more humble."

Williams was arrested in January 2007 in an incident involving drugs, guns, and an assault.

He opted for a nonjury trial and in August 2008, Brinkley found him guilty of assault, four counts involving carrying an unlicensed gun in public, and two drug counts.

Williams was sentenced to 11 to 23 months in prison - he served eight - and five years of probation, which is set to end in about three years.

He then resumed his rap career, and, according to Silver, gave up the street life in favor of aiming to become a superstar.

Meek Mill's first album, Dreams and Nightmares, was released Oct. 30, and he was in New York preparing to fly home for an Oct. 31 meeting with his probation officer when he got caught up in Hurricane Sandy.

According to Silver, Meek Mill and associates and a record company executive decided to drive but were stopped by Philadelphia police late at night after officers claimed to have detected the odor of marijuana from their Range Rover.

Though no drugs were found and no one was charged - Cogan said he has informed the city a lawsuit is coming - Williams was ordered to appear before Brinkley on Nov. 19.

According to DeSantis, Williams asked Brinkley to be able to finish his earlier tour rather than cancel appearances in the West between Nov. 23 and 30.

DeSantis said it was time for Williams to respect the courts and the break he got from Brinkley: "I mean, he was looking at five to 10 years in prison for gun and drug convictions."