A crucial prosecution witness in a Brooklyn judicial corruption case said yesterday he didn’t believe he was bribing state Supreme Court Justice Gerald Garson when he gave the judge cash and bought him meals and drinks.

The witness, ex-matrimonial lawyer Paul Siminovsky, also denied there was an agreement to bribe the Judge Garson or that the judge fixed divorce and custody cases that later came under suspicion.

Mr. Siminovsky was testifying at the trial of two former court employees. Judge Garson is awaiting trial on a felony charge of receiving bribes.

Mr. Siminovsky told jurors he bought the judge $10,000 worth of meals and drinks to secure more guardianship assignments in custody cases.

“I knew it was ethically improper,” Mr. Siminovsky said of his behavior. “I didn’t think it was a bribe.”

His testimony echoed arguments by Judge Garson’s defense lawyer that the judge committed ethics violations, not crimes.

Mr. Siminovsky also said the $1,000 he gave Judge Garson in a taped transaction was a “referral fee” for help in getting cases – not a bribe.

Defense lawyer Dominic Amorosa, who represents the judge’s former clerk, said the testimony gets Judge Garson “off the hook.”

Prosecutors said Mr. Siminovsky referred to what he thought at the time. “It’s how he rationalized committing crimes,” said Assistant District Attorney Noel Downey, who noted Mr. Siminovsky has testified that he and Judge Garson “committed crimes” together.

Prosecutors accuse Judge Garson of accepting meals and cigars from the lawyer in exchange for giving him preferential treatment and assigning him guardianship cases.

The two men on trial, retired court clerk Paul Sarnell and court officer Louis Salerno, are accused of taking bribes to steer cases to the judge.

The alleged mastermind behind that scheme is a Brooklyn electronics dealer who prosecutors say recruited worried Jewish divorce litigants and boasted that Judge Garson was “in his pocket.”