WikiLeaks founder Julian Assange’s protracted effort to fight extradition to Sweden suffered a body blow this week. Britain’s Supreme Court upheld the arrest warrant, issued in December 2010. After the court announced its split 5-2 decision, the justices surprised many legal observers by granting Assange’s lawyers an opportunity to challenge their decision—the first such reconsideration since the high-profile British extradition case from more than a decade ago against former Chilean dictator Augusto Pinochet. The decision came almost two years to the day after Pvt. Bradley Manning was arrested in Iraq for allegedly leaking hundreds of thousands of classified U.S. government documents to WikiLeaks. The cases remind us that all too often whistle-blowers suffer, while war criminals walk.

Assange has not been charged with any crime, yet he has been under house arrest in England for close to two years, ever since a “European Arrest Warrant” was issued by Sweden (importantly, by a prosecutor, not by a judge). Hoping to question Assange, the prosecutor issued the warrant for suspicion of rape, unlawful coercion and sexual molestation. Assange offered to meet the Swedish authorities in their embassy in London, or in Scotland Yard, but was refused.

Assange and his supporters allege that the warrant is part of an attempt by the U.S. government to imprison him, or even execute him, and to shut down WikiLeaks. In April 2010, WikiLeaks released a U.S. military video that it named “Collateral Murder,” with graphic video showing an Apache helicopter unit killing of at least 12 ...