President Obama asserted the unilateral power to "tweak" inconvenient laws in last Friday's news conference, underscoring his Administration's increasingly cavalier notions about law enforcement. So it's good that the judiciary—a coequal branch of government, in case the Administration forgot—is starting to check the White House.

In a major rebuke on Tuesday, the D.C. Circuit Court of Appeals issued an unusual writ of mandamus, which is a direct judicial order compelling the government to fulfill a legal obligation....