The United States and Switzerland are in advanced talks on a multibillion-dollar deal that would let several Swiss and European banks join a common settlement and avoid potential U.S. prosecution for helping wealthy Americans dodge taxes. As part of the agreement under discussion, known as a global resolution, U.S. government agencies would invite the banks to pay a fine, exit their undeclared offshore banking businesses for Americans, and turn over client names to the Internal Revenue Service (IRS) and the Justice Department. In exchange, the agencies would drop an ongoing investigation into the banks. It could not immediately be determined which banks could be invited to participate in the global resolution. The fines involved could collectively total several billion dollars, they said. Banks that opt out" of the deal could face heightened scrutiny from U.S. authorities, including a possible legal summons for client names from the IRS and tougher scrutiny by the Justice Department. A resolution would signal another strong blow to the Swiss tradition of client confidentiality, whose laws date to 1934 but whose tradition goes back centuries.