Right now, though, he is on the phone to a Detective Tellilo of the Boston police. The conversation is about a 14-year-old boy named Williams. Like so many in this mostly black neighbourhood, he was in trouble and needed help. The minister wants the officer to understand. "He is off the hook with the wire cut. He's crazy, a homicide waiting to happen. He needs to be in jail."
Indeed, Mr Rivers, 48, has just come in from the local courthouse, where he did his part to make sure the boy is incarcerated. He urged the judge to show no leniency. Earlier, he was at the boy's home to see the parents. "I told them their son was a sociopath. That one day he would meet the wrong version of himself who would put a bullet in his face. I said I was sending him to prison to keep him alive."
Helping dispatch one of his own flock hardly fits the image of the black pastor in inner-city America. But here he is playing a special role, one that has won him national attention. He is a co-founder of the Ten-Point Coalition, a group of black clergymen winning plaudits for help- ing spark the "Boston Miracle". He has made the cover of Newsweek, and soon he will make a speaking tour in Britain. Tomorrow he visits the White House.
It is not just that Boston is enjoying an almost unbelievable collapse in crime rates. Homicides have dropped 77 per cent since 1990, more than in any city in the country. More startling is this: the crackdown has been achieved without any sacrificing of racial peace between the police and the community: indeed, racial tensions here are at their lowest in a generation. Contrast this with New York, where the zero-tolerance policies of Mayor Rudy Giuliani have sparked the worst crisis in the city for years - exacerbated since the shooting of an unarmed African immigrant in the Bronx last month by four white police officers.
The birth of Ten-Point traces back to a dark day in May 1992. "The crack epidemic and gang violence was its zenith," says the Reverend Jeff Brown, one of the other three co-founders, recalling a funeral in the Morning Star Baptist Church in south Boston. As relatives were paying respects at the casket, a group of young men in black hoods entered and began chasing another youth in the congregation. Shots were fired and finally the man was stabbed nine times before the church's pastor threw himself on the man and barely saved his life. The violation at Morning Star shocked the church into action.
"We had to get out on the streets and make a connection with the kids," he explained. The following Friday and every Friday for the next several years, Mr Brown, Mr Rivers and a handful of other black pastors went on foot patrol in the dark of night in the most gang-ridden corners of the city to do just that.
It would be months before Mr Brown saw the first sign that they were making a difference. They were in a park they had visited many times before when a youth who every day stood sentinel at the gate into a chicken wire- fenced enclosure where drugs were traded - "a really scary-looking guy" - drew one of them discreetly over to one side. He wanted help in trying get his conscience back.
At first the ministers found trust on neither side. The gang members thought them crazy, and the police were outright suspicious. "The police spread stories that I was a heroin dealer," says Mr Rivers. "And then they told the real dealers that I was a snitch." Over time, though, trust built in both directions.
Christopher Winship, a Harvard sociology professor believes the coalition has been pivotal to the crime reduction. The ministers discovered that they had, in street language, "juice" in the eyes of the gangs. At the same time, says Prof Winship, the ministers regard as critical what Mr Rivers did on Friday: accepting that the worst offenders deserve punishment and, without flinching, advocating that punishment to the courts and the police.
This is the core of Mr Rivers's philosophy: the willingness of the black community at last to reclaim ownership of their own crime issues. Further, he sees in Ten-Point a germ of something much larger for African Americans, "an opportunity to launch a social movement," something that the black church, as the only institution with real reach among them, must spearhead. That is what he will be discussing with Vice President Al Gore tomorrow.
In Britain this summer he will be meeting church leaders, mostly in south London. We discuss the trip. Very quickly, we move on to an issue he has been reading a great deal about: racial policing in Britain and a study called the Lawrence Report.