It's useful to remember that the first instance of the government using "State Secrets" as a defense to withhold evidence was in a civil trial about culpability

It's useful to remember that the first instance of the government using "State Secrets" as a defense to withhold evidence was in a civil trial about culpability in the deaths of contractors that were testing Cold War equipment... ... and when the relevant documents were declassified, it was revealed that the secret the government was hiding was that test was run on a plane with a grossly-substandard maintenance history. https://www.thisamericanlife.org/383/origin-story/act-two-0 https://www.thisamericanlife.org/383/origin-story/act-two-0