Arlington residents last year elected a progressive top prosecutor backed by the county’s public defender. Both agreed on decriminalizing marijuana possession, ending cash bail and generally showing more leniency to people who break the law.

Now Commonwealth’s Attorney Parisa Dehghani-Tafti and Public Defender Brad Haywood are engaged in an unusual set of legal challenges to one county judge who they say has overstepped his authority and thwarted those efforts.

Dehghani-Tafti on Monday filed a motion in circuit court challenging Judge Daniel S. Fiore II’s handling of a plea agreement her office offered to a man allegedly found with 50 pounds of marijuana at Reagan National Airport. Separately, Haywood recently went to the Virginia Supreme Court and accused Fiore of violating his clients’ due process rights in ways that are “basic and rare” by refusing to schedule hearings for some defendants who are asking to be released from jail on bond or to have their sentences reconsidered.

Fiore and other judges in the Arlington Circuit Court have resisted Dehghani-Tafti’s efforts to stop prosecuting marijuana possession, saying she must offer good reason to drop each individual case. She also has a petition before the state Supreme Court saying they have infringed on her authority in those cases.

In an interview, Dehghani-Tafti broadly characterized the judges’ conduct as “judicial activism.”

Fiore, who has served as a circuit court judge since 2011, did not respond to requests for comment.

In the state Supreme Court, Attorney General Mark R. Herring (D) is representing Fiore against Haywood, while private attorneys are representing the judges against Dehghani-Tafti. In both petitions, the judges say they are making individual evaluations based on the facts and the law, which is a necessary part of the criminal justice system.

“Judges utilize discretion to broadly administer and ensure due process in given sets of circumstances,” attorneys for Fiore said in a recent filing. “This Court cannot broadly command Judge Fiore to ‘do justice,’ ” they wrote.

It is not clear when the state’s high court will weigh in on either petition.

Liberal prosecutors in other jurisdictions have faced what they see as similar pushback. The state Supreme Court sided with judges in Norfolk who had blocked the city’s chief prosecutor from dismissing all marijuana cases. In Boston, District Attorney Rachael Rollins fought successfully to the state Supreme Court after a judge refused her request to drop charges against a protester at a “Straight Pride” parade.

“We’re seeing in a lot of jurisdictions that have so-called progressive prosecutors or reformist prosecutors running, there often are other institutional actors that really balk and try to push back,” said Benjamin Levin, a professor at Colorado Law.

In Virginia, in response to that resistance, Gov. Ralph Northam (D) recently signed legislation that would require judges to dismiss charges when the defense and prosecution agree.

The most recent clash between Dehghani-Tafti and Fiore began in September when the judge rejected a plea deal for a 20-year-old alleged drug mule arrested in 2018 at National Airport, saying in a subsequent opinion that probation, with the possibility of having the felony charges dismissed, “does not address the level of rehabilitation needed” and “would not deter others.” The judge accused prosecutors of hiding from him that the defendant was accused of carrying 50 pounds of marijuana.

The case is now set for trial, but Dehghani-Tafti is asking for the rest of the Arlington bench to impose the original agreement on the grounds that Fiore “poisoned” any future judge with his “sensational” opinion.

Fiore’s actions “violate the rules of the court and the law of the land, and prejudice future proceedings,” she wrote.

Virginia judges must recuse from a case if they reject a plea agreement. Once that happened Fiore was barred from weighing in at all, Dehghani-Tafti wrote in her motion. Moreover, she argued, Fiore ignored the 17 days the defendant had spent in jail, 18 months of compliance with strict probation including 200 hours of community service and 150 clean drugs tests, and his cooperation with law enforcement.

The judge falsely tarnished the reputation of the defendant and her office, she wrote, by inaccurately claiming the man had a criminal record and accusing her of withholding information.

Fiore had raised the “problematic” amount of drugs involved at a March hearing but still appeared to be considering the deal, saying he was “trying to understand what you’re trying to do, and . . . trying to understand if I can do it, ” according to a transcript of the proceeding.

Given the change in Fiore’s posture between March and September, defense attorney Mary Nerino, a partner at Price Benowitz LLP, expressed concern that her client had become collateral damage in the dispute over decriminalizing marijuana possession.

“I do question the judge’s purpose and timing in filing that memorandum, and I’m concerned about the way it fails to address the heart of the plea agreement in my client’s case,” Nerino said. “The court’s complete omission of the substantial evidence regarding my client’s rehabilitation in its memorandum is likewise troubling, and it leads me to wonder whether it really was about my client and his specific case at all.”

Fiore has not yet responded to the joint filing by Dehghani-Tafti and Nerino. A hearing is set for Dec. 9.

People who have known Fiore as both a civil attorney and a judge say he is a thoughtful jurist committed to basing his rulings in the law.

Sudeep Bose, chairman of the Arlington County Bar Foundation, said Fiore’s background in complex civil litigation had prepared him to take on difficult questions about the balance of power between prosecutors, judges and defense attorneys.

“He is keenly aware of the law, and what he is doing is trying to shape his understanding of the law as it exists,” Bose said. “His drive is to better the body of law.”

In his petition, like Dehghani-Tafti, Haywood argues that the judge’s actions go beyond any discretionary scrutiny.

In one case, according to the filings, Fiore found a woman guilty of public intoxication even though she had complied with the terms of an agreement that would see her case dismissed. When she filed a motion to reconsider, he dismissed the case and moved to strike his ruling from the record as a clerical error.

In another case, according to a transcript, Fiore sent a homeless man to jail on a probation violation, although his case had been resolved by a lower court and prosecutors objected to the move. A public defender says he was blocked from arguing on the man’s behalf in court or scheduling a motion to reconsider. Eight days later, a clerk said, the man was released because the underlying warrant was issued in error.

Haywood argues that the judge has been vindictive, at one point adding a year to a man’s sentence because a public defender objected to the way the case was handled.

In that case, according to a transcript, Fiore initially sentenced the man to three years in prison, suspended, for grand larceny. When the defendant repeatedly violated probation, the judge amended the sentence to two years and ordered him to prison.

“I’m not willing to take a risk of restoring you to probation, and then you commit another crime in the community,” the judge said. When a public defender said, “I do need to object” to the change in sentence, Fiore said, “Okay. Then I’ll impose three.”

Virginia law requires bond hearings to be held within three days, “absent good cause shown.” Haywood alleges Fiore has “regularly” failed to hold such hearings, without explanation, and made rulings without notifying defense attorneys.

Haywood also has alleged that the court was blocking the release of recordings he planned to use as evidence of what he says were violations of due process. That issue has been resolved for the time being, with Clerk Paul Ferguson saying he would provide the recordings.

Fiore was reappointed by the state legislature to a new eight-year term last year, although he received relatively low marks on a survey of lawyers, jurors and court staff conducted for the state Supreme Court.

Fiore’s performance was rated as “Excellent” or “Good” by about 75 percent of respondents, but most other judges ranked much higher. Less than half of respondents said Fiore always displays knowledge of and fidelity to the law or respect for the people appearing before him. Before being reappointed to his seat last fall, Fiore told state lawmakers that the results were “disappointing and embarrassing” and that he was working on his temperament.