From the article: "Google argued that "just as a sender of a letter to a business colleague cannot be surprised that the recipient's assistant opens the letter,

From the article: "Google argued that "just as a sender of a letter to a business colleague cannot be surprised that the recipient's assistant opens the letter, people who use Web-based email today cannot be surprised if their communications are processed by the recipient's ECS [electronic communications service] provider in the course of delivery." The search giant goes on to quote a 1979 case, Smith v. Maryland, which found that "a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties."" If this argument stands, any surveillance becomes much easier to justify.