Lawyer for Walsh aide fights to stay

A defense attorney representing one of the Boston City Hall employees federally charged with extortion is fighting to stay on the case after prosecutors asked a judge to have him disqualified, according to court documents.

Defense attorney Thomas Kiley asked federal Magistrate Judge Judith G. Dein to allow him to file — under seal — a “response to the Government’s Motion to Disqualify” him, according to a motion filed Wednesday. Dein allowed the motion shortly after it was filed.

Kiley represents Tim Sullivan, Boston’s director of intergovernmental relations, against federal conspiracy and extortion charges. Sullivan was indicted last month and has been accused of working with Kenneth Brissette, Mayor Martin J. Walsh’s tourism czar, to hold back city permits from organizers of the Boston Calling music festival until they hired union stagehands.

Brissette also has been indicted.

Kiley declined to comment on the government’s maneuver, and federal prosecutors also declined comment.

It’s highly unusual for prosecutors to have defense attorneys disqualified, since people charged with a crime have a Sixth Amendment right to counsel.

“Unless he has some sort of conflict due to his involvement with the city, I can’t see why he would be disqualified. It’s really surprising, you don’t see it very often,” said Phil Tracy, a longtime criminal defense attorney who said he’s never been disqualified from a case.

“I’m really shocked that they’re going to this extreme.”