Update, 9/14/2012, 1:00 p.m. EDT: Information from filings made late Thursday by Dewey’s former executive director Stephen DiCarmine, former chief financial officer Joel Sanders, and former chairman Steven Davis have been added to the 13th, 14th, and 15th paragraphs below.

In a rash of filings Thursday made before a late-afternoon deadline, several parties connected to Dewey & LeBoeuf came out either for or against a proposed settlement plan that would collect $71 million from ex-Dewey partners in exchange for a release from Dewey-related liability.

Those opposed to the plan include an ad hoc committee of retired partners from Dewey predecessor firm LeBoeuf, Lamb, Greene & MacRae and an official committee of retirees created by the U.S. Trustee’s office as part of the Chapter 11 proceedings. Both groups have previously expressed concerns about the fairness of the proposed settlement and have asked U.S. Bankruptcy Judge Martin Glenn to appoint a neutral third party to oversee the case so that all parties are treated equitably.

The oppositions came the same day that an official committee of unsecured creditors, as well as informal groups of former Dewey partners, pledged their support for the settlement.

In its Thursday filing, the unsecured creditors committee, represented by Brown Rudnick partner Edward Weisfelner, explained that after “extensive analysis and deliberation,” it had decided that even though the amount of money being clawed back from former partners could be greater, the so-called partner contribution plan “is likely to generate a larger and quicker net return for the Debtor’s unsecured creditors than would otherwise be attainable through prolonged, expensive and uncertain litigation.”

The settlement’s approval, the committee said, is a necessary step toward arriving at a Chapter 11 plan and, ultimately, resolving the bankruptcy, which Dewey initiated May 28. At the same time the unsecured creditors said they oppose the participation in the settlement of former Dewey partners Stephen Horvath and Janis Meyer. Both have stayed on to help wind down Dewey’s operations and are being offered the same liability waiver as the rest of the plan’s participants without being asked to contribute any money. The unsecured creditors committee also opposes a provision in the plan that would allow money collected from partners in the United Kingdom to go toward the firm’s liquidation in that country rather than staying in the U.S.

Weisfelner notes in the motion that nearly 20 percent of the ad hoc committee, which is collectively opposed to the deal, signed on to it.

Meanwhile, in moving to block the settlement, the two former partners’ committees argue, among other things, that it should be filed in conjunction with a Chapter 11 plan rather than as a stand-alone motion. They also contend that the settlement was created by advisers with an inherent conflict of interest and that not enough analysis has been done to guarantee that the deal is fair.

In a dig at Dewey’s advisers, the official partners’ committee’s motion reads, “Although the PCP Motion is peppered with platitudes about the ‘complexity’ and ‘uncertainty’ of litigation (as if any litigation were simple and easy), the Debtor fails to provide any analysis—and, indeed, concedes that it performed none—regarding potential tort claims against former partners or when the Debtor became insolvent.”

The ad hoc committee’s motion contains its own shot at those currently shepherding Dewey through Chapter 11: “While the Debtor extols the virtues of an unprecedented settlement, the plain reason a settlement of this sort is ‘unprecedented’ is that it does not comply with the settlement standards imposed by Rule 9019 of the Federal Rules of Bankruptcy Procedure . . . and because it asks this Court to render a premature, impermissible advisory opinion.”

Dewey’s chief restructuring officer, Joff Mitchell, declined to comment Thursday.