Secret and probably illegal monitoring techniques cannot be used in court, because defendants have a right to know how evidence was obtained so they can challen

Secret and probably illegal monitoring techniques cannot be used in court, because defendants have a right to know how evidence was obtained so they can challenge it, and it then wouldn't stay a secret. Just because they don't currently have any methods they can base a court case on and put on public record doesn't mean they don't have other interception methodologies (whether through cryptographic weaknesses, CA attacks, compromising servers at Google / DropBox, cooperation from / insider double agents at Google / Dropbox / CAs, backdoors installed on clients, compromising user or employee login credentials and so on).