It should have come as no surprise that National Security Letters, which bypass the judicial oversight that would normally be required for a search warrant, have been subject to widespread abuse. But an anonymous Washington Post contributor reminds us of an additional factor: NSLs typically come coupled with gag orders, preventing those who’ve been served from questioning or publicizing improper requests for information. So not only is there minimal ex ante review, there are massive barriers to ex post accountability. The absence of either makes misbehavior more likely; the absence of both all but guarantees it.