To get the wiretaps, prosecutors had to stretch the law toward its breaking point. They argued that insider trading could amount to racketeering—one of the categories of law breaking that can be used to justify wiretaps. But this was itself a stretch. Racketeering laws were intended to be used against brutal gangsters, not traders taking advantage of informational asymmetries.
Clearly, the use of wiretaps in these cases goes far beyond the intent of Congress when it allowed racketeering as a justification for taps. But because the law was worded so broadly, it may be that Congress accidentally created room for this kind of legal creativity.
via Insider trading: Why do feds treat it like a mob crime? – CSMonitor.com.