FBI Director James Comey knows that if his agents get caught violating the Constitution, any evidence obtained from their searches will be invalid. Yet his agents can and do write their own unconstitutioanl search warrants. The Patriot Act calls these warrants by the euphemism "national security letters."
The list of third parties that can be subjected to an agent-written search warrant includes virtually all entities required by law to keep records. And recipients of these letters are forbidden from even telling anyone they've recieved one. It is this section of the Patriot Act that is being challenged by Twitter and Google in the Ninth Circuit Court of Appeals, explains Andrew Napolitano. The tech companies have apparently received many of these unconstitutional agent-written warrants, and they want their customers to know what the government is doing.