According to the Oregonian, Officer Jason Sery has filed a lawsuit in Multnomah County Circuit Court seeking to stop the District Attorney's proposed public inquest. He is represented by attorney Lawrence Matasar (for contact information for Mr. Matasar, go to www.osbar.org and search his last name). Matasar states in the article that his client will not appear at a public inquest if it is held prior to a grand jury proceeding. Matasar further stated that "my client has a constitutional right not to talk to anybody, but he already gave a detailed statement to the detectives. He didn't have to do that."
The court has not scheduled a hearing date on what will presumably be a preliminary injunction or temporary restaining order hearing, though it should be held soon. Oral argument should be open to the public.
If anyone else has any other information about this, like a case number, hearing date, etc., please follow up.