WASHINGTON, Aug. 16 -- A revoked visa does not come with a hearing. There is no appeal to an immigration judge, no published reasoning, and in most cases no explanation beyond a consular officer's determination that the holder is no longer eligible. That is the machinery the Trump administration has spent the past ten days pointing at pregnant travellers, and it is the machinery it reached for after the Supreme Court told it in June that it could not rewrite the Fourteenth Amendment.

Tommy Pigott, the State Department's principal deputy spokesperson, said on Saturday that the department had cancelled another 150 visas in recent days, pushing the total past 750 since the creation of a Birth Tourism Prevention Task Force. Secretary of Stat...