Here is an interesting article about how law enforcement officials have changed their tactics to catch Wall Street executives who are involved with insider trading. While wiretaps are traditionally thought of as tools to catch drug dealers, investigators decided to resort to using wiretaps in insider trading cases. Because insider trading is often done among, well, insiders, it was difficult for investigators to get inside tight groups of financial executives to see who was doing what. To circumvent this problem, investigators used whatever traditional methods they could to get an idea who was involved with insider trading and then closed the gaps through the use of wiretaps. When you have people on tape talking about using non-public information to make trades, it is a lot easier to get them to cooperate which, of course, leads to other suspects, more wiretaps, more cooperation and so on.