UPDATE: We have the filing that appears to have prompted Judge Sullivan to pursue a schedule for receiving briefs -- it's from 16 former Watergate prosecutors.

The filing: https://www.politico.com/f/?id=00000172-0b9e-dc3e-aff6-0f9f35990000 https://www.politico.com/news/2020/05/12/judge-slows-effort-drop-flynn-case-252725

The Watergate prosecutors argue that once a guilty plea is accepted, as it was for Flynn, it's final and becomes the juridiction of the courts. They intend to file an amicus brief presenting this argument more fully by May 21.

https://www.politico.com/f/?id=00000172-0b9e-dc3e-aff6-0f9f35990000

UPDATE: Judge Sullivan has *denied* the brief from the Watergate prosecutors, but seems to suggest it's just because he hasn't set a formal schedule for accepting briefs yet.