Taking on a fiduciary duty of loyalty and confidence, and then breaching it... that's serious.
Even when that fiduciary responsibility entails doing things that break the law in the jurisdiction in which you operate (the US) and in which your clients live (the US)?
I honestly am having a very hard time understanding your point here. You seem to be arguing that "duty" should trump legality. It does not.
Huh? I thought these were Swiss banks. As far as I know, he didn't break Swiss law.
Many organizations have a fiduciary duty which may break the law in some countries. For example, Tarsnap's fiduciary duty to protect secrecy almost certainly breaks the law in China, North Korea or Iran. Do you believe their duty to protect their client's data should not trump the laws of China?
UBS is a Swiss bank that also operates in the United States.
Birkenfeld is an American who, while in Geneva, participated in UBS activities which helped Americans hide money from the American government - which I think breaks the US law regardless of what jurisdiction the "help" happens in.
Note that Birkenfeld was arrested in the US after going to the US government with information - in your Tarsnap example, it would be like a Tarsnap employee traveling to China to tell the Chinese government that he/she helped circumvent Chinese laws. I don't think anyone would be surprised if the Chinese government then chose to prosecute that person.
As a business you can offer services to clients which may be illegal in some countries but fully legal in other countries - just don't go to the countries in which it is illegal and expect them to not prosecute you for helping their citizens get around their laws.
Also I think the term "fiduciary duty" is being misused in your Tarsnap example - correct me if I am wrong but Tarsnap is not managing or holding their user's funds for them (the "fiduciary" part of the term), but their data.
The broader definition of the word "fiduciary" (meaning guiding) doesn't require money to be involved, but any sort of responsibility with some expectation of duty. The root fiducial is used, for example, to refer to guide marks on a PCB design.
Even when that fiduciary responsibility entails doing things that break the law in the jurisdiction in which you operate (the US) and in which your clients live (the US)?
I honestly am having a very hard time understanding your point here. You seem to be arguing that "duty" should trump legality. It does not.