Metaphors and the Constitution: Wiretapping as Search
The controversy over NSA wiretapping involves two different legal issues. One is whether the actions are illegal, the other whether they are unconstitutional--whether a statute permitting them would be in violation of the Fourth Amendment. A group of legal professionals ranging from Richard Epstein to Lawrence Tribe have produced a summary of the arguments against the administration's position on both issues. In my view and theirs, the illegality of the actions is clear. They think the actions are also unconstitutional; I am less sure.
The Constitution says nothing at all about wiretapping. It says nothing about eavesdropping on conversations, which might seem the closest equivalent given 18th century technology. What it regulates are searches. Past court decisions have treated wiretaps as searches and so required warrants for them. But a wiretap is only a metaphorical search--it differs from a literal search in important ways, some of which raise problems for interpreting the Consitutional restrictions.
Suppose George has been having a possibly criminal correspondence with Thomas. The government gets evidence against George, obtains a search warrant, searches his house and finds letters from Thomas and drafts of letters to Thomas. They have obtained information about both George and Thomas, but they only needed a warrant against George, since only his house was searched.
Now fast forward a few hundred years. The government gets a warrant to tap Bill's phone--but what they are actually "searching" is not Bill's house but his conversations with George. Still legal--but the distinction between searching Bill and searching George has vanished.
Finally, consider a conversation between George and Usamah. Usamah is not an American, so the government is, constitutionally speaking, free to tap his phone without a warrant. But George is an American person--and they are listening to his conversation too. Do they need a warrant? Under the terms of FISA they do--but is that a constitutional requirement, or only a statutory one? Is the wiretap equivalent to searching both houses, or to searching Usamah's house and finding letters from George?