I mean there's https://www.schneier.com/blog/archives/2022/06/on-the-subver... for one. And you can look for instances of warrant canaries to see where else they've used the existing legal system.

As for covert ops, well, they're covert. I don't have any evidence (hence I said "I'm guessing") but that's how I understand secretive agencies do things. If you look at all of the agencies involved in Stuxnet, you'd get the idea that allied countries' secret services tend to work together (or for each other) to some degree when it suits them.