The Cato Institute is currently playing host to an important libertarian debate over civil liberties and the law enforcement response to the Boston Marathon bombings. The starting point was a recent essay at the Hoover Institution's Defining Ideas journal by libertarian New York University law professor Richard Epstein, who argued, "given the stakes, law enforcement officials should follow all leads, even if that means more surveillance and ethnic profiling."

That piece prompted a response by Cato's Jim Harper, who argues that Epstein "sounds needless anti-privacy notes." Here's a portion of Harper's argument:

Where I think Professor Epstein goes wrong insofar as he wants law enforcement to have its way is in setting aside "technical difficulties" and "means-ends" questions as peripheral. For me, the Fourth Amendment's bar on unreasonable searches and seizures demands coordination between means and ends in light of the technological situation (both in terms of doing harm and discovering it). It is not a given that government action is reasonable, and no amount of priority given to a threat makes an incoherent response reasonable and constitutional.

Cato has now published a response by Epstein, which contends:

Harper would have a stronger case if he had tried to comment constructively on serious proposals that are put forward. But to take an ill-advised a priori position that does nothing to advance either the protection of human life and human property, both private and public, is inconsistent with any sound libertarian position. Remember that libertarians like myself, and I hope Harper, regard the protection of both as the primary function of the state. Harper's careless and imprecise invocation of the Fourth Amendment cannot conceal this fundamental truth.

Read the whole debate from the beginning by starting with Epstein's initial essay, Harper's response, and Epstein's reply.