NEW YORK, March 29 (Reuters) - When a high-profile lawyer serves on a high-profile criminal case, what obligation does he have to disclose his connections to prosecutors?

That is the question posed after an unusual round of discussion that occurred on Tuesday in a sexual assault trial in State Supreme Court in Manhattan.

In the case, off-duty police officer Michael Pena had been accused of sexually assaulting a woman at gunpoint in Manhattan. A trial began in mid-March.

On Tuesday, before the jurors reached a partial verdict, one juror raised questions about another juror - Juror #2 - saying he had some concerns about #2's relationship with the prosecution team.

Juror #2 turned out to be Lloyd Constantine, a veteran of New York legal circles, founder of the commercial litigation firm Constantine Cannon, and one-time adviser to former Governor Eliot Spitzer.

Constantine is now counsel at Constantine Cannon. The firm's managing partner is Richard Aborn who ran against Manhattan District Attorney Cyrus Vance in the 2009 Democratic primary.

Moreover, according to a New York Times account of Tuesday's hearing, Constantine said in the courtroom that he had a social relationship with Vance, and had played tennis with him.

When the question arose on Tuesday, Acting Supreme Court Justice Richard Carruthers called a sidebar conference with Ephraim Savitt, Pena's defense attorney, prosecutors and Constantine.

According to Savitt, Carruthers asked Constantine a variety of questions and his answers left both sides satisfied. Both parties agreed to keep Constantine on the jury.

"My sense of it is that Constantine was a fair and impartial juror, that's why I didn't ask for him to be excused," said Savitt. He says he wouldn't consider bringing up the Constantine issue in any future appeal.

A spokeswoman from the Manhattan DA's office declined to comment.

On Tuesday, Pena was convicted on criminal sexual assault and predatory sexual assault; on Wednesday, Carruthers declared a mistrial on the remaining rape charges, because jurors were deadlocked. 

ACTUAL PREJUDICE REQUIRED

In an interview after the trial, Constantine said he knew both Aborn and Vance, gave $5,000 to both men's campaigns, has played tennis with both men, and "broken bread," with both men.

He also said he was forthcoming about the connections during the voir dire process, when the court distributed a questionnaire to potential jurors and asked about their relationships with law enforcement.

"I answered all the questions they posed during voir dire completely truthfully and honestly," said Constantine. He described a voir dire questionnaire as "very cursory" and said it didn't drill down into his web of legal relationships gained from practicing law for 40 years. The only reason to disclose those relationships would have been to get out of jury duty, Constantine said.

"You'd have to be practicing at the bottom of the Pacific Ocean not to know a good number of prosecutors, as well as defense lawyers. I just wasn't going to play the game," said Constantine.

The information that Constantine had relationships with both Aborn and Vance "probably" should have been disclosed during voir dire, said Ronald Minkoff, a litigator at Frankfurt Kurnit Klein & Selz who counsels clients on ethics matters.

However, "I don't know if it automatically disqualifies one from being a fair and impartial juror in any cases from the Manhattan DA's office," said Minkoff. The district attorney's office tries thousands of cases a year, a fact that would lessen Constantine's connection to an individual case, Minkoff added.

Nevertheless, Carruthers did the right thing by allowing Constantine to remain on the jury, said Bennett Gershman, an ethics professor at Pace Law School. "There's a very high burden to show bias. It's not enough that a juror is going to be slanted in favor of one side or another," said Gershman.

A 1982 Supreme Court decision in Smith v. Phillips codified the high threshold by which true bias must be shown so as to cause a mistrial, said Gershman.

"The safeguards of juror impartiality, such as voir dire and protective instructions from the trial judge, are not infallible; it is virtually impossible to shield jurors from every contact or influence that might theoretically affect their vote," then- Chief Justice William Rehnquist wrote in that opinion.

After the trial, Constantine said he was unruffled by the flap.

"Apparently a lot of people are weighing in with their experts on this part of it. But I'm a big boy and I've been around a long time and I can take it," he said.

(Reporting By Carlyn Kolker; additional reporting by Noeleen Walder)

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