Rachael Rollins is an unapologetic change agent, the likes of which we haven’t seen in the recent history of Boston politics.

But it is important to understand that her current battle with a Boston Municipal Court judge over whether to prosecute counterprotesters at a Straight Pride’ parade is about more than whether to try a single defendant. It’s a window into a power struggle over how to administer justice.

“What I find interesting is that no one ever questioned prosecutorial discretion when it was moving toward the status quo,’’ Rollins said from Ireland in a telephone interview. “But when it isn’t, it’s an abuse of discretion. Since time immemorial, prosecutors have been able to determine when they choose [to prosecute] or not.’’

Boston Municipal Court Judge Richard Sinnott refused to allow a Suffolk County prosecutor’s routine motion — at Rollins’s approval — to skip prosecution of a nonviolent protester earlier this week. That immediately set off a firestorm. Sinnott, who was appointed to the bench two years ago by Governor Charlie Baker, then escalated matters dramatically: He had defense attorney Susan Church jailed for several hours for contempt after she dared to cite case law she said Sinnott was ignoring.

Whatever you make of details of the case, things have gone completely off the rails when a district court judge can have a lawyer hauled off in handcuffs simply for annoying him. Whatever happened to judicial temperament?

Rollins sees a broader point in Sinnott’s behavior toward Church.How, Rollins is asking, does such a judge treat the defendants — most of them black and brown — who appear before him?

“We can’t have judges whose skin is so thin that someone reading a case results in them being put in a cell,’’ Rollins said. “But we have to understand that this happens every day to criminal defendants. And [for them] it’s not three hours in the courthouse — it’s huge bail, long sentences, and massive disparities based on wealth.’’

Rollins has appealed Sinnott’s ruling on the nonviolent protester to the Supreme Judicial Court, where a single justice is expected to rule. She said she’s confident that her petition has hundreds of years of law on its side, and will prevail. The case is an important one, partly because Sinnott isn’t the first judge to balk at Rollins’s policy of declining to prosecute nonviolent crimes. She hoped this ruling will confirm, once and for all, that judges can’t tell her whom to prosecute.

Rollins is one of a wave of prosecutors around the country elected to rethink how the criminal justice system operates. She suspects she has run into even more entrenched establishment opposition than some of the others. As far as Rollins is concerned, she is the systemic change voters selectedand judges have no right to block that change.

“Take a look at who those people are,’’ she said. “They’re used to being in power they’re used to making decisions about poor people, even though none of them are. They love talking about us and making decisions for us and none of them have allowed us to sit at the table. That’s all changing now.’’

She points out that just two of the state’s Superior Court judges are African-American, and that, at every level, judges rule on the lives and liberty of people who don’t look like them.

“We need a judiciary that better reflects the community it’s appointed to serve,’’ she said.

Rollins is certainly correct when she says that her use of discretion is challenged in a way her predecessors’ was not. There’s nothing novel about deciding that nonviolent offenses can be handled outside a courtroom — or not at all. Prosecutors make judgments all the time, with none of this drama.

If Rollins seems combative — itself a loaded term — she says it’s because she feels a great sense of urgency to address a system that has historically treated people of color and people without means unfairly.

“I think change is really hard. And I’m urgent about this because I think we’re decades behind where we need to be and I’m firm in my position. I want people to know that I’m taking positions that I think are fair and just.’’

Ultimately, fighting Sinnott at the SJC is just the latest battle in a series. Rollins never had any illusions that breaking with the policies of her predecessors would be painless, but she believes the public overwhelmingly supports her push for change.

“It’s still the best job I’ve ever had in my life, and it’s an honor and privilege to serve,’’ Rollins said. “No matter the outcome, we’re going to get clarity, and I think that’s going to be good for Suffolk County.’’

Adrian Walker is a Globe columnist. He can be reached at adrian.walker@globe.com. Or follow him on Twitter @adrian_walker.