There’s a showdown taking shape between the Financial Accounting Standards Board and corporate legal professionals who still have big problems with FASB’s plan to require more disclosure about certain loss contingencies.

FASB decided to extend the comment period for its latest proposal to require companies to say more in their financial statements about unresolved legal problems that may have an impact on the company’s financial condition. The board voted to extend the Aug. 20 comment deadline to Sept. 20 to give companies more time to study it and voice any concerns they may have.

And they still have plenty, according to the Association of Corporate Counsel, a professional group of corporate attorneys that has repeatedly told FASB greater disclosure of unresolved legal problems is tantamount to laying out the legal strategy for the opponent in a lawsuit. “Another 18 days won’t change our minds,” said Susan Hackett, ACC senior vice president and general counsel in a statement. “ACC and our co-signatories would prefer that FASB spend that time reviewing our comments and reconsidering their proposed changes.”

Chairman Bob Herz said the board decided to extend the comment period because companies have told the board the original 30-day comment period was too short. Companies faced conflicts with quarterly reporting deadlines, other major accounting proposals that require study, and summer vacation plans for key people, said Herz. “The board members heard these concerns and agreed that an extension of the comment period would be helpful to the board’s due process,” he said.

The proposal is FASB’s second attempt to implement new disclosure requirements that would end the last-minute surprises investors sometimes face when companies settle huge legal actions with little or no forewarning. The first proposal in 2008 required companies to provide some estimates of possible outcomes, but FASB’s subsequent proposal stuck closer to requiring companies to provide information that’s otherwise available from public sources, such as court dockets.

Hackett says the proposed new disclosure requirements still would expose companies to greater liability and litigation, and the planned effective date of Dec. 15, 2010, isn’t workable. “These proposals, if codified, will impede rather than encourage responsible and timely reporting,” she said.