A novelist and former prosecutor who is suing Brooklyn District Attorney Charles Hynes for firing him over a book he wrote is a brat who complains when he doesn’t get his way, the D.A.’s lawyer said yesterday.

“When he doesn’t get what he wants, he starts pouting and he acts like a child,” the lawyer, Patricia Miller, said of author Robert Reuland as the trial in the civil-rights suit got under way in federal court in Brooklyn.

Ms. Miller told jurors Mr. Reuland’s suit was about “his desire for publicity,” while Mr. Reuland contended he was demoted and fired for writing a book and speaking his mind.

In opening arguments and early testimony, the case seemed to focus less on the Constitution and more on the insular, often poisonous politics that infect even a district attorney’s office.

Mr. Reuland testified that he lost his prestigious, beloved job in homicide in 2001 after boasting to a New York Magazine reporter that Brooklyn was “the best place to be a homicide prosecutor. We’ve got more bodies per square inch than anyplace else.”

Mr. Hynes was outraged, according to Mr. Reuland, who at the time was about to publish his first novel, “Hollowpoint,” about a fictional Brooklyn homicide prosecutor.

Mr. Reuland quickly lost his coveted position in the homicide bureau, along with his office’s nice view and furniture – including a credenza, he said.

He told jurors that he soon found himself crammed into a windowless room with no chairs where, instead of prosecuting homicides, he was charged with prosecuting low-level crimes such as public urination.

“It was the high point of my legal career and it was taken away from me for a ridiculous reason,” said Mr. Reuland, 40. “I felt profoundly humiliated and punished.”

Ms. Miller quickly lashed into him, suggesting he went to the homicide bureau to promote “Hollowpoint,” which he wrote while working for Mr. Hynes.

She said Mr. Hynes moved Mr. Reuland out of homicide after realizing he had been “conned.”

Ms. Miller also derided Mr. Reuland’s performance as a prosecutor as “abysmal.”

“That’s the story of Mr. Reuland,” she said. “And that’s not a violation of his First Amendment rights.”

On the stand, Mr. Reuland, who worked at Wall Street law firms before joining Mr. Hynes’s office in 1997, defended his courtroom skills.

He acknowledged that having been a homicide prosecutor gave his two books – his second novel, “Semiautomatic,” appeared last month – a “flavor of authenticity” and possibly boosted sales.

But he insisted it was “nutty” to think he had wanted to be a homicide prosecutor to promote his writing.

“Please, that’s totally absurd. Totally absurd,” he said, shaking his hand.

Mr. Reuland said his comment about Brooklyn’s murder rate was not meant to insult Mr. Hynes. During a meeting with Mr. Hynes after the story appeared, he said he tried to placate his boss, who Mr. Reuland contends was concerned about protecting his reputation as a crime fighter.

Mr. Reuland said the men chatted peacefully at first, but Mr. Hynes flew into a rage after Mr. Reuland said Brooklyn still had more work to do in lowering the murder rate. After the meeting, Mr. Reuland was assigned to a less-prestigious trial bureau and, months later, forced to resign.

Mr. Reuland’s suit seeks unspecified damages and back wages. The trial is expected to last four days. Mr. Hynes likely will take the stand today.