Sort of. The Jabara case is a nifty example of how the government can assert state secret without queering the entire trial. The defendant is entitled to the most exculpating inference that the withheld data would provide, if shown.
http://www.freerepublic.com/focus/f-news/1550960/posts?page=238#238 <- scroll UP for more
Thanks,
I have wondered what would happen if Fitzgerald were to say: "I'm willing to stipulate that Libby was busy with a lot of top secret stuff, so there is no need to produce it".