Wikipedia and many other websites are shutting down today to oppose a proposal in Congress on foreign Internet piracy, and the White House is seconding the protest. The covert lobbying war between Silicon Valley and most other companies in the business of intellectual property is now in the open, and this fight could define—or reinvent—copyright in the digital era.

Everyone agrees, or at least claims to agree, that the illegal sale of copyrighted and trademarked products has become a world-wide, multibillion-dollar industry...