The intelligence community’s top lawyer, Robert S. Litt, told colleagues in an August email obtained by the Washington Post that Congressional support for anti-encryption legislation “could turn in the event of a terrorist attack or criminal event where strong encryption can be shown to have hindered law enforcement.”

So he advised “keeping our options open for such a situation.”

Litt, the general counsel in the office of the Director of National Intelligence, is well known for making flip comments. But in this case, his private observation offered insight into just how eager some officials are to come up with examples to support their argument that end-to-end encryption — which precludes law enforcement from intercepting communications between two parties — presents an imminent danger to national security.

The Post story was about the lack of momentum for legislation that would require firms to be able to unlock their customers’ smartphones and apps under court order.

A senior official granted anonymity by the Post acknowledged that the law enforcement argument is “just not carrying the day.” He told the Post reporters: “People are still not persuaded this is a problem. People think we have not made the case. We do not have the perfect example where you have the dead child or a terrorist act to point to, and that’s what people seem to claim you have to have.”

On Tuesday, Amy Hess, a top FBI official, told reporters that the bureau has “done a really bad job collecting empirical data” on the encryption problem. FBI Director James Comey has attempted to provide examples of how law enforcement is “going dark,” but none have checked out. Only Manhattan District Attorney Cyrus Vance has been able to provide an example of encrypted technology maybe blocking one possible lead in a murder investigation.

Caption: Robert Litt at a Senate Judiciary Committee hearing.