A warranted search of personal records, based on probable cause, is a constitutional function of government. In this case, the suit filed against the government gives rise to discovery which makes it legal and constitutional to seek subpeona for these records. If it can be shown that the requested records cannot produce useful evidence, the subpeona can be denied. You have the same right (to seek evidence in your favor from an opponent) if a suit is filed against you, either criminal or civil.