Argument in Andrew Miller's appeal of the district court's contempt order for failing to appear before the Mueller grand jury will not be until October, per today's order from the DC Circuit. 
Here was the earlier filed notice of appeal. Miller is the Roger Stone associate who has, thus far, refused to testify before the grand jury. Background: washingtonpost.com/world/national…
Miller is challenging Mueller's authority, specifically to subpoena him to testify and provide records. US District Judge Beryl Howell disagreed, in a 93-page decision. When he still didn't appear, he was held in contempt. He is now appealing that civil contempt finding.
Incidentally, the appeal comes as a third judge — after two in Manafort's cases — ruled against challenges to Mueller's authority. Wednesday's ruling came in Concord's challenge in the Russian troll farm case. Here's the conclusion:
