The law requires government agents to get warrants to open first-class letters.
But when he signed the postal reform act, Bush added a statement saying that his administration would construe that provision “in a manner consistent, to the maximum extent permissible, with the need to conduct searches in exigent circumstances.”
As in many other cases, the signing statement contains a weasel term that supposedly covers Bush’s ass. The maximum permissible extent was established in the law Congress had just passed: it’s illegal for the US government to read people’s mail without a warrant.
Phrases like “the maximum extent permissible” give the impression that the law is just an inconvenience to be surmounted. A few constitutionalists believe something like that, with “permissible” defined only constitutionally; however, there is no serious constitutionalist argument for the Patriot Act(s) and Homeland Security Bill.