The problem stemmed from certain bundled messages that internet companies sometimes packaged together and transmitted as a unit. If even one of them had a foreign target’s email address somewhere in it, all were sucked in.
After the N.S.A. brought that issue to the court’s attention in 2011, a judge ruled that it violated the Fourth Amendment, which bars unreasonable searches. The agency then proposed putting the bundled messages in a special repository to which analysts, searching through intercepts to write intelligence reports, would generally not have access. The court permitted that type of collection to continue with that restriction.
But last year, officials said, the N.S.A. discovered that analysts were querying the bundled messages in a way that did not comply with those rules. The agency brought the matter to the court’s attention, resulting in a delay in reauthorizing the broader warrantless surveillance program until the agency proposed ceasing this collection practice.
