The BitTorrent peer-to-peer file sharing protocol designed by Bram Cohen has proved to be one of the great disruptive inventions of the Internet. Removing the need for a large central data source means large files can be distributed efficiently with minimal strain on the network.

Of course, its decentralized operation has helped pirates who no longer have to store data on servers which are vulnerable to seizure. Although this illegitimate use attracted much of the early publicity after its launch in 2001, BitTorrent is now...