A federal appeals court panel in San Francisco gave a largely chilly reception yesterday to Wal-Mart’s bid to block a massive class action lawsuit alleging sex discrimination in pay and promotion practices at its stores.

Two of the three 9th U.S. Circuit Court of Appeals judges assigned to the case, Harry Pregerson and Michael Hawkins, seemed skeptical about the retail giant’s arguments, while a third, Andrew Kleinfeld, was more supportive of the company. The lawsuit claims that female employees at Wal-Mart stores made 5% to 15% less on average than their male counterparts.

Judge Hawkins, whom attorneys involved in the case viewed as the likely swing vote on the panel, made clear early in the hour-long session that he was troubled by the disparities within Wal-Mart’s workforce. “Two-thirds of hourly employees are women. One third of salaried employees in management positions are women,” observed Judge Hawkins, an appointee of President Clinton.

“That’s when you look at the nationwide statistics,” Wal-Mart’s lawyer, Theodore Boutrous Jr., said. “That does not tell you what’s going on at the store level or really even at the regional level. These decisions are being made at the promotion point by thousands of store managers.”

“There’s no evidence that those managers … were making common or even discriminatory decisions,” Mr. Boutrous said, according to a recording of the session that was posted on the Web.

Judge Kleinfeld suggested the plaintiffs’ lawyers wanted to introduce bureaucratic inefficiency into Wal-Mart’s wildly successful business model, which gives store managers significant discretion in pay and promotion. “They’re saying you should not be allowed to do that. It should be like the post office. You should have nationwide criteria and anyone with a master’s degree gets ahead of anyone who just has a bachelor’s,” said the judge, who was appointed by President George H.W. Bush.

Judge Kleinfeld seemed doubtful that Wal-Mart’s policy of giving great leeway to its managers was enough, when coupled with the pay disparities, to authorize a nationwide class action. “Wal-Mart has a national policy of not having a national policy” with respect to promotion criteria, the judge said.

Judge Pregerson, who was appointed by President Carter, praised the ruling of the judge who gave the go-ahead for the historic class action last June, Martin Jenkins of the U.S. District Court in San Francisco.

Judge Pregerson, 81, also took the highly unusual step of publicly dressing down Mr. Boutrous over the tone of the company’s brief. “It has language in there that’s a little arrogant, that’s a little offensive towards the district judge, talking about the judge being prolix and wordy and long-winded, trampling on Wal-Mart’s due process rights,” Judge Pregerson said. “Do you regard this as an effective way to present written advocacy?”

“That was our hope,” Mr. Boutrous replied.

“You slam the district judge,” Judge Pregerson insisted.

“We didn’t mean any disrespect,” explained Mr. Boutrous, a partner with a Los Angeles-based firm, Gibson, Dunn & Crutcher. “You can be courteous when you say those things. This is like someone fighting in the streets or alley,” Judge Pregerson said, adding that he believed Wal-Mart owed Judge Jenkins an apology.

Mr. Boutrous said the judge’s order excluding individual-store evidence from future phases of the case violated the company’s right to defend itself, but Judge Hawkins said he doubted such testimony would be insightful.

“There is no case that has ever held that a defendant has a due process right to an individual hearing challenging every class member,” the lawyer who argued for the plaintiffs, Brad Seligman, said.

The three-judge panel issued no ruling yesterday. The losing party can seek review from a larger, 11-judge appeals court panel or the Supreme Court.