Mayor Giuliani yesterday praised a former top aide who has spent his post-City Hall career clashing in court with the Bloomberg administration.

“I would imagine he is thought of at the present City Hall the way we used to think of the ACLU,” Mr. Giuliani said yesterday of his mayoral operations chief, Randy Mastro. “That’s a nice thing to be — the guy who sues them the most and defeats them the most.”

Courts don’t publicize win and loss tallies for individual lawyers, but Mr. Mastro — a vocal ally of Mr. Giuliani’s presidential bid — has represented clients who oppose the current mayor on some of his administration’s signature causes.

When Mr. Bloomberg sought to ban trans fats from city restaurants last year, McDonald’s hired Mr. Mastro to challenge the effort. Other clients of Mr. Mastro’s include disappointed bidders hoping to sell wholesale produce at Hunts Point Market and two others seeking to install public toilets on the streets of New York City.

Mr. Mastro hinted at how his ex-boss could repay him for his years of loyal service: Mr. Mastro circled the name of his law firm, Gibson, Dunn & Crutcher, under the heading “The Supreme Court” in the program for the Jewish Theological Seminary’s Judge Simon H. Rifkind Award luncheon. Mr. Mastro was given the award.

Gibson Dunn is a firm where several partners, including a former Bush administration solicitor general, Theodore Olson, are conservatives and members of the Federalist Society.

When he saw the program with the name of the Mr. Mastro’s firm circled, Mr. Giuliani joked: “You want to be the entire Supreme Court?”