India has seen a sharp erosion in civil liberties under the government of the Hindu nationalist Prime Minister Narendra Modi. “Journalists, academics, and others have faced harassment and intimidation when addressing politically sensitive topics,” Freedom House observes in a recent report.

The extent of this intimidation has become personally apparent. My journalist brother, Siddharth Varadarajan, was served notice Friday—coincidentally, his 55th birthday—to appear before the police of Uttar Pradesh, India’s most populous...