(Dow Jones) A former office branch manager's arbitration victory against Oppenheimer & Co. is best described as hollow. But ask that manager, James F. Dever, or his lawyer to explain just how hollow, or why, and you won't get much of an answer.

A confidentiality order bars Dever and other parties from revealing any details of testimony, hearing transcripts and the proceedings themselves. That edict from the arbitration panel, as part of its October finding, is highly unusual and perhaps unprecedented, according to lawyers. It raises questions about just how much power arbitrators should have in keeping proceedings secret.

"I've never heard this come up, be mentioned, or thought about" in 20 years of practice, says Brian Carlis, a Lawrenceville, N.J.-based lawyer who represents brokerages and investment advisors.

Dever managed Oppenheimer & Co.'s Boston office from 2001 to 2007. He accused the firm of retaliation and damaging his reputation, according to an order available on Finra's Web site, after an underling came under suspicion of fraud. Dever sought $5 million plus other damages, but was awarded $73,939, according to the order.

Arbitrators issued a gag order during the proceedings after the Boston Globe reported on Dever's case in September. That order was lifted when the panel made its finding, and when it put the new confidentiality requirement in place.

Dever is asking a Massachusetts state court to vacate the secrecy order. Ironically, he felt obliged to ask that court to seal its file while it considers his request.

"We want to challenge the confidentiality provision, while being careful not to violate it-or even be perceived as violating it-until the court ultimately rules on the issue," said Angela Magary, Dever's lawyer in Andover, Mass. Dever directed a request for comment to her. A Finra spokesman declined to comment.

Some details of the case can be gleaned from the public record. Dever's Form U5, which brokerages file with regulators when a broker leaves the firm, shows his troubles dating back to at least 2006. That's when Massachusetts regulators accused Oppenheimer of failing to properly supervise a broker in Dever's office, Stephen J. Toussaint.

Toussant was accused of bilking an elderly couple through theft, forgery and churning. He later pleaded guilty to fraud charges in federal court, and is serving a 46-month sentence.

Oppenheimer agreed to pay a $1 million fine to the state in 2007. Dever was demoted two weeks later and then, he alleged, was pressured to leave, according to a Boston Globe report. He said company lawyers had told him not to reveal everything he knew about Toussaint to regulators, and that he had resisted those instructions.