I think the short answer is that they could get away with it if they kept it secret, but if the courts found out about it that alone could be enough to through

I think the short answer is that they could get away with it if they kept it secret, but if the courts found out about it that alone could be enough to through the entire case. > The N.S.A.’s protections for attorney-client conversations are narrowly crafted, said Stephen Gillers, an expert on legal ethics at New York University’s School of Law. The agency is barred from sharing with prosecutors intercepted attorney-client communications involving someone under indictment in the United States, according to previously disclosed N.S.A. rules. But the agency may still use or share the information for intelligence purposes. [1]: https://www.nytimes.com/2014/02/16/us/eavesdropping-ensnared-american-law-firm.html https://www.nytimes.com/2014/02/16/us/eavesdropping-ensnared...