A proposed legal settlement that could deliver about $64 million to American Express cardholders and up to $11 million to plaintiffs’ lawyers is under assault from rival attorneys who say the company should be paying much more.

In recent weeks, notices about the litigation, which relates to the company’s handling of foreign currency transactions, have landed in the mailboxes of American Express card members across the country.

While the flyers outline the proposed settlement, they say nothing about the dust-up among the law firms concerned, all of which have pending lawsuits that could be dismissed if a federal judge approves the deal.

Those challenging the pact say American Express conducted what amounts to a “reverse auction” by shopping around until the company found a group of attorneys that would accept the lowest settlement offer.

“American Express’s chief settlement negotiator has given sworn testimony that the settlement was achieved by pitting one set of plaintiffs’ lawyers against the other,” the critics wrote in court papers filed last month. When one group of attorneys “proved themselves insufficiently pliable,” the company moved on to another, the brief argued.

The chief proponent of the settlement is a New York law firm, Garwin, Bronzaft, Gerstein & Fisher.

The rival firms contend that the deal Garwin Bronzaft took was actually worse than what American Express earlier offered a San Diego firm, Lerach Coughlin. Further complicating matters is the fact that while Lerach Coughlin initially rejected that deal, it has now agreed to the proposed settlement.

A partner at Garwin Bronzaft, Kevin Landau, declined to be interviewed about the case. He said terms in the settlement bar him from discussing it publicly. The lead attorney handling the matter for Lerach Coughlin, Frank Janecek Jr., did not return a call seeking comment for this story.

At least 10 class action cases have been filed against American Express regarding its foreign exchange practices. Many of the cases contend the company failed to fully disclose a 1% or 2% conversion fee it imposed on charges made in foreign currency. Several suits made other claims, accusing American Express of shortchanging cardholders by using the least favorable exchange rate on a given day and secretly adjusting rates in the company’s favor.

American Express has denied wrongdoing and asserted that it made all disclosures required by law. However, it has agreed to pay up to $75 million to resolve the cases. Only cardholders who submit claims will be paid, likely by credits to their account that would roughly correspond to the 1% to 2% fee charged since 1997.

The settlement also includes an additional payment for cardholders who charged purchases in Turkey. American Express allegedly gave those customers bad rates because the company’s computers couldn’t handle all the decimal places involved in converting Turkish lira, which often trade at more than one million to the dollar.

A lawyer challenging the settlement, Michael Caddell of Houston, said in an interview that the deal’s advocates only accounted for the percentage exchange fees and not the other ways the company allegedly manipulated overseas transactions.

“The long and the short of it is, this settlement was reached without considering all the possible claims,” Mr. Caddell said. “There was never any meaningful examination of any other issue in these cases.”

The firms fighting the settlement are Caddell & Chapman, as well as Lieff Cabraser and Girard Gibbs, both of San Francisco.

One lawyer backing the settlement portrayed opposition to the deal as routine. “Any significant class-action settlement tends to draw objectors. There are attorneys – that’s the nature of their practice, and this one is no exception,” said James Baum of Berkeley.

However, there are indications that the federal judge responsible for approving the settlement, Cecilia Altonaga of Miami, is giving some credence to the deal’s critics.

In a move described as “extremely rare” by those challenging the settlement, Judge Altonaga ruled last fall that the critics could demand documents and testimony about the claims explored by lead attorneys on the case.

The lead plaintiffs’ lawyers opposed such discovery. They have also sought to block any exploration by the rival firms of the negotiations that led to the settlement.

Last week, a federal magistrate in Miami, Ted Bandstra, ruled that records of those negotiations should be opened to the attorneys trying to unravel the pact.

The cases against American Express were filed after a California judge ruled against Visa and MasterCard in a similar case in February 2003. Following a six-month trial, the judge ruled that the credit-card companies were deceptive in failing to disclose conversion fees on billing statements. He also said the fees bore no relation to any costs incurred by Visa or MasterCard.

Plaintiffs’ lawyers said that decision, which has been appealed, could result in refunds of as much as $800 million to cardholders.

Mr. Baum, whose firm brought the Visa and MasterCard suit, said American Express’s willingness to settle was a direct result of the earlier ruling. “American Express saw the fate that befell Visa and MasterCard, and they wanted to make peace,” he said.

The credit-card companies argue that the fees they charge are far lower than the commissions that foreign exchange brokers charge travelers who convert paper currency.

Mr. Baum rejects that comparison. “Thomas Cook and Travelex have to build buildings, have to buy currency, and pay someone to sit in a little booth,” he said. “The fee is nothing but an opportunity for the credit-card network to enhance revenue at the expense of cardholders.”

A prominent critic of class-action settlements, Lawrence Schonbrun, said he sees the dispute over the American Express deal as driven primarily by the rival law firms’ fear of being shut out of the legal fees that the company has agreed to pay.

“What is the benefit to the general public? … I think very little,” Mr. Schonbrun said. “It doesn’t mean anything except it’s going to get lawyers tens if not hundreds of millions in fees.”

Mr. Schonbrun acknowledged that the provision for direct refunds to customers is better than in some other settlements. “Could it be worse? Yes. They could have gotten a coupon,” he said.

Judge Altonaga is scheduled to consider the merits of the American Express settlement at a hearing on March 14. Those who wish to opt out of the lawsuit, or to object to the deal or the request for attorneys’ fees, must do so by February 14. Cardholders requesting a refund of their foreign exchange fees have until April 13 to submit a claim form, which can be found on the Web at www.lipumasettlement.com.

Opponents of the American Express deal have also questioned why claim forms are required, since the company has records of all transactions since 1999. The company and lead attorneys on the case say making the refunds automatic would be impractical.

Under the settlement, if less than $30 million in claims are made, American Express will make a donation to charity that will bring it’s payment up to $30 million.

If the claims and other expenses exceed the $75 million cap, checks and credits to individual cardholders will be reduced accordingly.

Regardless, the agreement dictates that the amount the court awards in attorneys’ fees will be paid in full.

The lead plaintiff in the American Express case in Miami is a professor of anthropology at the University of Miami, Edward LiPuma. Mr. LiPuma did not respond to a call seeking comment.

Under the settlement agreement, he is entitled to ask the court for a $10,000 “incentive award” from the settlement fund.