Unlike compact little England that once ruled them, India and the U.S. are each vast, multiracial, federal democracies that boast supreme courts and written constitutions. Until this month, however, India differed from the U.S. in one vital respect: its constitution was thought to give its legislatures the same freewheeling power as that of Britain's House of Commons—a power to jail critics for contempt with no judicial review whatever.
Now the Indian Supreme Court has changed all that with an historic decision, laying down clear guidelines of court power in a manner reminiscent of the pioneering U.S. Supreme Court under Chief...