D.L. Cromwell Investments, Inc., Lloyd Bierne, David S. Davidson, Eric S. Thomas, and Matthew Greenwald v. Nasd Regulation, Inc.

JACOBS, Circuit Judge.

Plaintiffs-appellants D.L. Cromwell Investments, Inc. (“Cromwell”) and individual Cromwell employees, all members of the National Association of Securities Dealers, Inc. (“NASD”), have been the subject of ongoing investigations both by NASD Regulation, Inc. (“Regulation”), which is an investigatory arm of the NASD, and by federal prosecutors. They have sued to enjoin NASD Regulation from compelling them — under threat of sanctions authorized by NASD Rule 8210 — to submit to on-the-record interviews, arguing that NASD Regulation is a willing tool of the prosecutors and…