PHILADELPHIA (Reuters) - Lawyers for Meek Mill on Tuesday asked a Pennsylvania appeals court to overturn a 2008 drugs and gun conviction that has kept the rapper on probation for a decade and made him a celebrity advocate for U.S. criminal justice reform.

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Defense lawyers said the Philadelphia judge who has long overseen Meek Mill’s case is no longer impartial and has become overly involved in his life, once visiting a homeless shelter to check he was doing mandated community service.

Attorney Kim Watterson also said the sole witness against Meek Mill at his 2008 trial was a discredited drug squad officer who is no longer with the Philadelphia police force.

A city prosecutor agreed with Watterson, supporting her request for a new trial and new judge for the artist known for hits like “All Eyes on You” and “Going Bad.”

“There is more than a substantial record that this judge acted as prosecutor, advocate, cross-examined witnesses, and made herself a fact witness,” said Watterson, calling for the recusal of judge Genece Brinkley.

Prosecutor Paul George, arguing for the Philadelphia District Attorney’s Office, said it was standard practice to hold a new trial when an officer deemed a “critical witness” was subsequently deemed untrustworthy by a police force.

He urged the three-judge panel to replace Brinkley.

“The standard is to disqualify a judge when a significant majority of the community might question a judge’s impartiality,” George said.

Meek Mill, 32, whose legal name is Robert Williams, appeared in court wearing a dark suit and did not speak during the hearing.

The three judges made few comments but appeared favorable to both defense and prosecution positions.

Judge Jack Panella pointed out that there were other officers present at the time of Meek Mill’s alleged drug offenses who could testify.

In November 2017 Brinkley sentenced the rapper to up to four years in prison, saying a pair of arrests violated probation conditions she set following his 2008 convictions.

The arrests, one for popping a wheelie while shooting a New York City music video, did not result in convictions.

The hefty sentence became a cause celebre for musicians, celebrities and criminal justice reform campaigners who said it was typical of a U.S. legal system that treats minorities unjustly.

Meek Mill was jailed for five months before the state’s top court granted him bail.