Dan Stickler, a lawyer for Massey, argued during Tuesday's hearing that the disclosure harms the company's position as it defends against other pending lawsuits.
"Someone in the plaintiffs' camp has breached the agreement," Stickler told the panel. "It's tantamount to breach of contract."
Stickler said inspecting all correspondence from the plaintiffs' lawyers to the claimants should show whether they did enough to keep the settlement confidential and whether sanctions may be necessary.
Bruce Stanley, a lawyer for the plaintiffs, said his team had nothing to do with the leak and does not know who's responsible. He said his team took pains to abide by the confidentiality agreement, and to notify the claimants of it. Stanley said he even tried to dissuade the AP reporter from disclosing at least some details when contacted for comment.
Even if a claimant or someone associated with one leaked the letter, the remaining plaintiffs should not be punished as a result, Stanley told the judges.
Judge James Mazzone, who heads the panel, noted that the judges have not received the settlement terms. Stickler said it included no specific punishment for breach of its confidentiality.
Mazzone said after announcing the post-hearing agreement that the judges would rule on the matter following the closed-door review.