Duty to Clients or Country?

It is about to happen to me. Next week, I anticipate receipt of a subpoena to testify in Federal Court about a mediation over which I presided 18 months ago. I have already received the Court order telling the parties to request my declaration (which I refused to do.) Here's the deal: U.S. District Court civil rights action. No offers made and the case did not settle before me. 18 months later, the case went to trial and the Plaintiff got a "modest" verdict. The parties are now fighting about attorneys fees. The court seems to be persuaded by the Defense's position that the case could have been settled for the amount of the verdict at the mediation. (But of course, it wasn't!) I discarded my notes a year ago, but have orally communicated with both lawyers that my recollection is that no offer was made. Certainly, the case didn't settle--so what difference does it make? It's a perilous position for the court or the attorney's to take: if you fail to accept a low-ball offer, you may not be able to recover your fees if you do better than that at trial unless it's huge. While up until now I considered the attorneys and their clients to be "my clients", I intend to refuse to testify under the confidentiality protections. I guess I feel a little differently about my "duty to country" in the face of a Subpoena to testify to a Federal Judge about matters I consider to be strictly confidential. I'm left feeling angry that the Court may determine this in ways that contravene the policies favoring mediation through confidential communication. I'm lefting feeling angry that I will have to go through the expense of refusing to comply with a Federal subpoena in order to safeguard this process.