US Federal law requires that phone companies etc make available provisions so Law enforcement can wiretap lines when they have a court order. Currently their are no provisions or if their are they are not being talked about for Law enforcement to tap VOIP conversations.
I imagine that those that are involved in criminal activity are smart enough to realize this and are probably exploiting the technology. With all of the data transmission methods now though I wonder at what point does it become unfeasible for law enforcement to do their job properly. Kind of scary but all we can hope is that they at least attempt to keep up with technology to protect the citizens of this country. [The Register]