Underwood and Assistant District Attorney Noel A. DeSantis told the judge that Williams violated his five-year probation by traveling outside Pennsylvania without telling Underwood his exact itinerary.
Federal law requires Underwood to know Williams' whereabouts at all times - especially if he's outside Philadelphia - so she can notify authorities in those jurisdictions.
Williams is supposed to file travel plans listing time, date, address, and phone number of every place he will be when not in Philadelphia. He's supposed to call her when he arrives and leaves each site, Underwood said.
The problem, said Underwood, is that Williams has not been consistently letting her know where he is or will be until after he gets there.
That, explained Williams, is part of the life of an aspiring rap superstar.
"The problem is that I don't know," Williams said. "It changes every day."
Williams said people in his entourage - many of whom sat in the gallery - do his itinerary. He said he contacts his lawyer, Gary Silver, who gets the travel plans and changes to Underwood.
"But you're supposed to call me," Underwood said during a free-form two-hour hearing where Silver, DeSantis, Underwood, and Williams kept interrupting and talking over each other.
"You folks are just going to have to work it out," said Brinkley, visibly miserable from a bad cold and sounding more like a marriage counselor than judge.
Indeed, Williams, Silver, and cocounsel Dennis Cogan asked for a divorce: a new probation officer.
"That's not going to happen," said Brinkley.
Williams, on probation from a 2008 drug and gun conviction, was sentenced to 11 to 23 months in prison, served eight, and began five years' probation in the fall of 2009.
He then resumed his rap career and gave up the street life in favor of becoming a superstar.
Williams told Brinkley he believes Underwood is just trying to make his life tough because they knew each other growing up in the same North Philly neighborhood.
"It's like a game with my life," said Williams, dressed for the hearing in black V-neck sweater and pants, white shirt, and tie.
Williams said Underwood has made him wait in a public area of the probation office where he is besieged by autograph-seekers and several probation officers asking him to critique their rap demo tapes.
"Celebrity cuts both ways," interjected DeSantis, who added that Williams' use of Twitter to criticize her and Underwood had resulted in anonymous death threats.
Given his celebrity and art form, the judge told Williams, that was like "shouting fire in a crowded theater."
"You need to take off your hat as Meek Mill and put on your hat as John Doe, unknown person, and do what you're supposed to do," Brinkley said.
Brinkley outlined some new guidelines for Williams to follow and set a status hearing June 28.
"You need to try to get this right next time," Brinkley added.
The judge ruled that Williams did not violate his probation when he was on a tour bus belonging to the rapper French Montana on Feb. 28.
The bus was parked outside a hotel on Columbus Boulevard near the Ben Franklin Bridge after a nearby concert when a drive-by gunman fired into a crowd outside, killing a New York man.
Contact Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.