"One danger of a never-ending government investigation into people's financial transactions is mission creep. A Treasury Department spokesman told The [New York] Times that the information mined from Swift - which includes millions of records - cannot be used for anything except terrorism searches. But there is little to guarantee that will continue to be the case."

"Congress, which has given the administration many new powers to conduct terrorism investigations, needs to judge whether this was what it had in mind. The original Patriot Act made major changes in money-laundering laws that provided for the use of administrative subpoenas. But the Judiciary chairman, Arlen Specter, was quoted yesterday as questioning whether their use in the Swift investigation has been too broad. The committee has already scheduled an oversight hearing this month, at which Attorney General Alberto Gonzales is slated to appear. The senators should take the opportunity to look deeper."

"So far, the only check on the executive branch appears to have come from the Swift executives themselves, who grew increasingly concerned when what they envisioned to be a short-term program seemed on its way to becoming permanent. It was at their insistence that the controls the government now cites were put into place. An outside auditing firm is now used to verify that investigators have real intelligence leads behind their requests for information. That is all to the good; it is clear that when it comes to defending their customers, international banking executives are far more aggressive than, say, American telephone company executives."

>>> "Curiously, maybe Congress will wake up at this point and realise that they've got a tiger by the tail. When that transaction tracking starts getting used for non-terrorist purposes, there are going to be some very annoyed people."

I'd re-phrase this to 'When [people begin to think] that transaction tracking starts getting used for non-terrorist purposes, there are going to be some very annoyed people.' I'd also suggest that people will immediately think that the information tracking is being used for non-terrorist purposes.

Indeed a worrying development.
And as the article suggests, I would expect the big bad guys to know how to avoid this kind of detection anyway. Leaving on the smaller, less important terrorist groups prone to detection on the SWIFT network. And of course ... Innocent John Doe.