The FBI wants to exempt its burgeoning national database of fingerprints and facial photos from a federal law that gives Americans the right to sue for government violations of the Privacy Act, such as refusing to tell a person if he or she is in the system. The bureau also wants to shield its data storehouse from other Privacy Act rules, including one that lets people ensure that the information the government holds about them is accurate. The proposed exemptions, published in May in the Federal Register, have stirred objections from an array of privacy and civil rights advocates.