This patent was originally owned by Certicom, now part of Blackberry. One of the inventors was Scott Vanstone who's excellent book, Handbook of Applied Cryptography lives on my desk.

The patent seems to indicate that Dual EC is known to be usable for escrow, something that the NSA surely knew. But given the pedigree of the authors, it must have been known by a bunch of other people well before the March 2013 publication date.

There's something odd going on here.