The Swiss decision has two key points: Over the course of 12 months, banks will be allowed to turn over to American authorities general statistical data on their work with American clients. More significantly, the US can seek concrete account details - with names of taxpayers - if the US. Senate gets its act together and passes a double-taxation treaty already green-lighted by Bern. The latter all but guarantees that a client's name will be disclosed. But so, possibly, does the former: The IRS already has a trove of information from previous disclosures, including names of bankers, and prosecutors are working with authorities in other tax haven countries, notably Liechtenstein, to scare up details on Swiss banks and their clients. Around a dozen banks have been ensnared in the U.S. investigation, including UBS (UBS), Credit Suisse (CS), HSBC's Swiss arm, Julius Baer and two cantonal, or regional, banks. Wednesday's decision by Bern, a significant moment in the annals of Swiss secrecy and client confidentiality, awaits approval by Swiss parliament, where some factions appeared incensed by the appearance of caving in to U.S. demands. a leading Swiss finance professor at Zurich University, called the decision "blackmail by a large nation," referring to U.S. threats to indict banks should Switzerland not agree to cooperate. Prosecutors indicted Wegelin, Switzerland's oldest bank that once had Napoleon as a client, in 2012, and the bank pleaded guilty in January, effectively shutting its doors for good. Still, under U.S. tax laws that make willful nondisclosure a felony, American taxpayers who are eventually outed to the IRS under the Swiss decision could face draconian fines, penalties, and criminal charges. More than five-dozen Americans have been charged in recent years for tax evasion through Swiss and other offshore banks. So it's critical that Swiss bank account holders come forward to the IRS before the agency finds them. Unlike the U.S., Switzerland does not generally consider tax evasion to be a crime.