As some of you might be aware, the conservation group Sea Shepherd has made it its business to harass Japanese whalers in the Antarctic Sea. They allege that Japan's whaling ships are violating both the International Convention for the Regulation of Whaling and Australian law. I think they have some good law on their side, although then again I'm biased - I had up close encounters with Humpback Whales in Antarctica. For more background, check out the book Harpoon.
Recently, the BBC reported that the Sea Shepherd's efforts have reduced Japan's whale harvest by over half. This is certainly a victory for the whales. However, it also raises interesting legal questions. Most governments allow citizens to enforce the law as "deputy sheriffs," but within the confines of courts and traditional litigation. In the whaling case, activists did seek and obtain a court judgment against the whalers, but to no avail. As such, when is it appropriate for citizens to use other means to enforce the law when governments can't or won't? Where is the boundary between neighborhood watch programs and vigilanteism?