Pakistan, Sept. 5 -- India has spent the better part of eight decades investing political capital in a particular distinction: Pakistan, it told the world, was born in religion while India was anchored in citizenship. The claim survived wars, pogroms, insurgencies, communal riots and constitutional emergencies because New Delhi could still invoke the architecture of a secular republic. That architecture now looks increasingly occupied by another idea.

The allegations made by journalists Shaheen Khan and Nafisa Khan deserve to be read against that larger retreat, according to which Delhi Police detained and assaulted them while they were covering a September 3 event in Saket attended by Union Home Minister Amit Shah and Delhi Chief Minist...