The Central Intelligence Agency’s torture of detainees, and the National Security Agency’s warrantless wiretapping of Americans’ international communications, were two of the most controversial programs our government implemented after Sept. 11. Both are now widely considered to have been illegal, even though both were authorized by official legal analyses that were withheld from the public — a phenomenon known as “secret law.”The notion of secret law is as counterintuitive as it is unsettling. When most of us think of law, we think of statutes passed by Congress, and we take for granted that they are public.Statutes, however, are only one kind of law. When the secret surveillance panel known as the Foreign Intelligence Surveillance Court, or FISA court, construed the Patriot Act to allow bulk collection of Americans’ phone records, that interpretation became part of the statute’s meaning. When President Obama issued procedures and standards for using lethal force against suspected terrorists overseas, agency officials were bound to follow them.