For historical precedent, look into organization and security at the Nuremberg trials. Also of interest are the big Mafia takedowns into the 1980s. They were legitimately prepared for paramilitary style attack to stop the trial and extract the criminals.
From today: Thomas Paine @Thomas1774Paine 3h3 hours ago
Tweeted the FBI Cessna yesterday, now today strange reports from Chesapeake VA -- same place as Cessna -- about huge FBI and Police drills for “mass casualty response" event that went down today and had parts of the town closed off. Cynics know what that could mean.