@nitinkhanna @adrienne That, unfortunately, is something LUKS doesn't handle. Once the system is online and the passphrase provided to unlock the volume, it stays unlocked until the system is shut down.
I'm working on the basis of "if we're at the point where the government is going to surgically remove the system from the datacenter while keeping it powered on and I get no prior notice that they're attempting that so I can't shut the system down, we're more screwed than I as a small provider can handle," to be honest.