It’s make or break for the internet as we know it. Unless Congress acts this summer, the Obama administration will end U.S. protection of the internet, handing authoritarian regimes the power they have long sought to censor the web globally, including in the U.S.

The battle lines were drawn last week when the Obama administration backed a plan submitted by the Internet Corporation for Assigned Names and Numbers, or Icann, to free itself in September from the U.S. oversight that has kept the internet open since the 1990s. In...