After abandoning their case last year against two senior aides to Boston Mayor Marty Walsh accused of attempted extortion, federal prosecutors could re-file charges against the men.

Prosecutors for the U.S. Attorney’s Eastern District of Massachusetts first charged city tourism chief Kenneth Brissette and inter-governmental affairs director Timothy Sullivan in 2014, alleging that the men had used their positions to illegally coerce the Boston Calling music festival into hiring union labor it didn’t want or need for its festival, at the time planned to be held on Boston’s City Hall Plaza.

Both men pleaded not guilty; in legal briefs, they argued they were lawfully advocating for union labor, and merely implementing an open preference by the Walsh administration for union labor on city property.

The case never went to trial. Last year, the case was dismissed after federal district judge Leo T. Sorokin ruled that, in order to make the case for extortion, prosecutors would have to prove that Brissette and Sullivan were seeking to benefit personally in pushing Boston Calling to hire members of the IATSE Local 11. Sorokin dismissed the case after prosecutors acknowledged they could not meet that burden of proof.

Prosecutors appealed Sorokin’s ruling to the First Circuit Court of Appeals. On Thursday, judges for the First Circuit agreed with the appeal, ruling that Sorokin had erred in constraining the definition of extortion in the case.

That means prosecutors could re-file charges against Brissette and Sullivan (protection from “double jeopardy” doesn’t apply here because the case never went to trial).

A spokesperson for the U.S. Attorney’s Eastern District of Massachusetts said that the office is reviewing the judge’s ruling and its options but declined to say whether prosecutors intend to re-open the case.

A spokesperson for Boston mayor Marty Walsh had no comment on the recent appellate ruling.

Despite this victory, there may be reasons federal prosecutors would opt not to pursue charges again.

The U.S. Attorney’s Office lost another federal extortion case involving union labor in 2017, after charging members of the local Teamsters union with attempting to extort the television show Top Chef.

The jury found each of those defendants not guilty, leading many legal observers to speculate that the government’s chance of winning its case against Brissette and Sullivan was slim.

And at least some in the legal community see the allegations against the men — and First Circuit’s ruling — as deeply flawed and ideologically driven.

“Frankly, it’s a very ideological approach. ... This court has taken a pro management and anti-labor stance,” said Harvey Silverglate, an attorney and longtime critic of federal prosecutorial overreach.

“Brissette and Sullivan did not personally benefit from the pressure they were seeking to put on the employer here, for the benefit of the [union],” Silverglate said. “And the idea that they can be convicted of essentially extortion is absurd.”

Silverglate said he believes federal courts are employing increasingly anti-union ideology in this and similar decisions.

Attorneys for Brissette and Sullivan did not immediately return a request for comment.