The challenger, a former state legislator threatening the party favorite, was kicked off the primary ballot in a district attorney race in Queens after a judge ruled that the signatures he had gathered were not valid. The man, seeking to beat Richard A. Brown, lost an appeal, paving the way for Mr. Brown to easily defeat a Republican in the heavily Democratic borough.
That was in 1991, and it was the last time Mr. Brown faced an opponent for the office.
Now 83, Mr. Brown has been re-elected six times, most recently in November, a victory so routine there was no public celebration. Concerns about his health — Mr. Brown has been open about his struggles with Parkinson’s disease — and rumors that his office is increasingly managed by his top associates have done little to churn up opposition.
However, in an era when criminal justice reform is an increasing part of the conversation in New York City, and district attorney seats in Brooklyn and Manhattan have turned over in recent years — or, in the case of Staten Island and the Bronx, will on Jan. 1 — some people have begun asking where Mr. Brown’s challengers are.
“He’s run a good office,” said Arnold N. Kriss, a defense lawyer and political adviser to Mr. Brown. “It’s very hard to be a candidate against a sitting district attorney when there’s nothing to run against.”
Others said his long tenure was a reminder that the city’s antiquated political machines were still a force in Queens.
“It undermines democracy when there is no real challenger to step up to run against incumbents,” said Dick Dadey, the executive director of Citizens Union, a government watchdog.