The House Democratic surveillance memo is out, and it should worry Americans who care about privacy and due process. The memo defends the conduct of the Justice Department and Federal Bureau of Investigation in obtaining a series of warrants under the Foreign Intelligence Surveillance Act to wiretap former Trump campaign adviser Carter Page.

The Democrats argue that Christopher Steele, the British former spy who compiled the Trump “dossier” on which the government’s initial warrant application was grounded, was credible. They...