In the 1907 case of Houghton v. Meyer, Postmaster General, the United States Supreme Court dealt with issues related to postal regulations and freedom of speech. The plaintiff, Houghton, was a publisher who had been denied mailing privileges by the Postmaster General due to alleged violations of postal laws prohibiting obscene literature. The specific content in question was a medical book discussing sexual topics which were deemed inappropriate at that time. Houghton argued this denial violated his First Amendment rights to free speech and press. The court ruled against Houghton stating that while Congress cannot interfere with the press's right to publish its views on any subject, it does have power over mail delivery under Article I Section 8 Clause 7 of Constitution (Postal Clause). Therefore it can refuse mail service for materials violating established standards or laws without infringing upon First Amendment rights. This decision upheld government’s authority over regulating what could be sent through U.S Postal Service while also acknowledging limitations imposed by constitutional protections for freedom of expression.

In the dissenting opinion for Houghton v. Meyer, Postmaster General (1907), Justice Harlan argued that the majority's decision was a violation of constitutional rights. He disagreed with their interpretation of Congress' power over postal services and believed it did not extend to censoring mail based on its content. Harlan emphasized that freedom of speech is protected by the First Amendment and should apply to all forms of communication, including mail. He also pointed out that if Congress could ban certain types of letters from being sent through the post office, they could potentially use this power to suppress political dissent or other unpopular views. Therefore, he concluded that while Congress has broad powers over regulating postal services, these powers must be exercised in a way consistent with constitutional protections for free speech and expression.