A clash of the titans is shaping up in Moscow, as the Bank of New York Mellon later this month will battle it out with the Russian Federation over a $22.5 billion money laundering case.

Each side is bringing in heavy firepower.

Representing the Bank of New York Mellon, one of America’s oldest financial institutions, is a former U.S. attorney general and governor of Pennsylvania, Richard Thornburgh. He is joined by the law firm Boies, Schiller & Flexner, perhaps best known for representing Vice President Gore in his Supreme Court fight against President Bush over the 2000 presidential election.

Representing the Russian side is a famed Harvard law professor, Alan Dershowitz. He is partnering with G. Robert Blakey, one of the foremost experts on the Racketeer Influenced and Corrupt Organizations Act, on which Russia’s case is based, and a retired U.S. federal appellate judge, George Pratt. The three lawyers will travel to Moscow next week to give testimony on behalf of the Russians.

“This is a very, very serious lawsuit,” Mr. Dershowitz, who has represented such defendants as O.J. Simpson and the financier Michael Milken, said. “And I am really looking forward to going to battle with some great lawyers.”

The Russian Federal Customs Service is suing the bank over a money laundering scheme from the 1990s, when two Russian émigrés moved $7.5 billion to American accounts from Russia via unlicensed wire transfers. The Bank of New York, which was founded by Alexander Hamilton in 1784, agreed to pay the American government $38 million in fines, among the largest ever assessed against a bank in the U.S. for money laundering.

The Russians claim they, too, should be awarded a fine — they are looking for $22.5 billion in damages — and are basing their argument on the RICO statute. It is a very rare example of the racketeering statute being argued in a foreign court.

“RICO was clearly intended for international application,” Mr. Dershowitz said. “There is no such thing as local American law; you have to look at global terrorism, global organized crime, and global banking. It would strip RICO of much of its power if it were interpreted only to apply domestically.”

Mr. Thornburgh and his team plan to argue that “the U.S. Congress never intended that the U.S. RICO statute be applied to foreign courts,” according to a release from Bank of New York Mellon. The bank will also argue that under the decision by the Department of Justice, the bank “was never found to have committed any violation of U.S. criminal law by any U.S. court as required for RICO,” and that the Russian government has failed to provide proof of damages, which is also required under RICO.

Even if the Russian courts decide against the bank, which many experts predict will happen, it would be difficult for the plaintiff to collect on the money outside of Russia, where the Bank of New York Mellon does not hold significant assets, the lawyers for the bank said. The bank is also prepared to argue in courts around the world where it does have assets that the case should be dismissed.

Mr. Dershowitz and his team have a different interpretation.

“A lot of this case will turn on what the bank and its officers have said in the past, and what they have said will come back to haunt them,” he said. “There has already been an admission by high-ranking officials at the bank of wrongdoing, so the bank cannot credibly say, ‘Yes, bank officials admitted it, but we are not responsible.'”

Mr. Dershowitz added that while “the liability issue seems relatively clear cut, the question now is, does the admission by people of wrongdoing carry over into a civil context? Yes it does, and I think the admission itself will take us there.”

There is also the question of whether a judgment against the bank would be enforceable. The Bank of New York, which last year merged with Pittsburgh-based Mellon Financial Corp. to become one of the world’s biggest custodian of financial assets, is arguing that the Russians are trying to collect back taxes that were lost when Russian companies laundered the money, rather than pursuing the criminal act of money laundering. According to American and European law, a foreign country cannot use courts in America to collect taxes.

“It is not a tax issue, because there are all the elements of financial fraud,” Mr. Dershowitz said, adding, “The plaintiffs will be able to demonstrate substantial losses.”

As for the difficulty of tracking down the award from the Bank of New York Mellon should the Russian Federation win the case, “it would be very embarrassing for the bank to run around the world arguing that the judgment of a United Nations country is not enforceable,” Mr. Dershowitz said. “They would look like they were trying to evade justice, so if there is a judgment against the bank, they will pay it.”

The bank’s stock traded down 4.2% yesterday, to $42.65. There has been considerable selling by insiders at the bank in the last month, with a total net sale of 288,560 shares in May alone. The insiders who sold the bulk of the stock included the co-head of the global effort to integrate Bank of New York and Mellon Financial, Steven Elliott, and the executive chairman of Bank of New York Mellon, Thomas Renyi. The sales could be interpreted as a loss in confidence in the bank, or merely an effect of the change in management resulting from the banks’ merger last year.

As for the hiring of Mr. Dershowitz and the other lawyers, the Bank of New York Mellon said in a statement, “The retention of a celebrity lawyer by the plaintiff’s Miami-based attorneys cannot change the facts or the law in this case, which make clear that the claim is invalid and represents a misapplication of U.S. RICO law.”