In this April 2, 2019, file photo, recording artist Meek Mill speaks at a gathering to push for drastic changes to Pennsylvania’s probation system, in Philadelphia. (AP Photo/Matt Rourke, File)

Lawyers for Meek Mill will ask an appeals court Tuesday to overturn a 2008 drug and gun conviction that has kept the rapper on probation for a decade and made him a celebrity crusader for criminal justice reform.

Defense lawyers believe the city judge who has overseen his case and sent him to prison in 2017 over minor parole violation has become overly involved in the performer’s life _ once checking on his community service efforts at a homeless shelter _ and lost her impartiality.

And, they say, the only prosecution witness at the nonjury trial was a drug squad officer whose credibility is now in doubt.

“When a trial judge injects herself into a probationer’s personal and professional life and creates an appearance of bias and, on top of that, makes multiple legally erroneous rulings, the whole judicial system suffers,” appellate lawyer Peter Goldberger wrote in a defense brief filed in advance of Tuesday’s arguments before Pennsylvania Superior Court .

The retired officer, Reginald Graham, is on an internal do-not-call list of police officers District Attorney Larry Krasner won’t use in court because of credibility concerns, according to a brief Krasner’s office filed in support of the new trial bid.

Although he was not charged federally with the other officers in the narcotics unit, Graham resigned from the police department prior to being formally dismissed,” Krasner’s office wrote, referring to a 2015 police corruption trial that ended with the acquittal of six officers. “The Commonwealth cannot call a witness whose credibility it mistrusts.”

Mill, whose real name is Robert Rihmeek Williams, became a champion for criminal justice reform after Judge Genece Brinkley sentenced him in 2017 to two to four years in prison for minor probation violations. He spent five months in prison before a court ordered him released last year.

He has hired a large team of top criminal lawyers to fight his conviction and probation issues, prompting the judge herself to hire a high-profile city lawyer to defend her actions.

“She’s a tough judge across the board,” said the judge’s lawyer, A. Charles Peruto Jr. “When you have this kind of money and fame you use it to your advantage to try to show she’s prejudiced against him. . If he wins, it just demonstrates that he’s above the law.”

At the 2008 trial, Graham testified that the 19-year-old Williams pointed a gun at him during the arrest outside his southwest Philadelphia home. Williams has acknowledged having a gun but denied pointing it at police. Brinkley found him guilty and sentenced him to concurrent jail terms of just under one year and two years, followed by 10 years of probation.

Williams, now 32, has frequently tangled with the judge over terms of the parole, especially over reporting requirements and travel rules that he says conflicts with his soaring music career.

Brinkley, after a 2015 hearing that included testimony from Williams’ then-girlfriend, superstar Nicki Minaj, said she “has done nothing but try to help the defendant.”

Williams, whose top-selling albums include the 2015 “Dreams Worth More Than Money” and last year’s “Championships,” is a fixture at NBA games in Philadelphia and has the support of many high-profile celebrities and athletes.

He appeared in last month’s season finale of “Saturday Night Live,” performing beside DJ Khaled, John Legend, SZA and other artists in a tribute to slain rapper Nipsey Hussle.

A documentary on his legal travails, produced by music mogul Jay-Z, is set to be released next month.