Lovejoy v. United States was a Supreme Court case decided in 1965. The case involved a challenge to the constitutionality of the federal obscenity statute, which prohibited the interstate transportation of obscene materials. The petitioner, Lovejoy, was a bookseller who had been convicted of violating the statute by sending obscene books through the mail. Lovejoy argued that the statute violated his First Amendment right to freedom of speech. The Supreme Court rejected this argument, holding that the statute was constitutional because it was narrowly tailored to serve a legitimate government interest in protecting the public from obscene materials. The Court also held that the statute did not violate the Due Process Clause of the Fifth Amendment, as it provided adequate notice of what was prohibited and did not impose an undue burden on interstate commerce. In the end, the Supreme Court upheld the constitutionality of the federal obscenity statute, and Lovejoy's conviction was affirmed. The decision established that the government could regulate obscene materials without violating the First Amendment.

In the Supreme Court case of Lovejoy v. United States, Justice William O. Douglas wrote a dissenting opinion in which he argued that the majority’s decision was wrong and should be overturned. He believed that Congress had not intended to criminalize peaceful protest when it passed the statute at issue in this case, and thus there was no basis for convicting Lovejoy under it. Furthermore, he argued that even if Congress did intend to criminalize such protests, then doing so would violate First Amendment rights of free speech and assembly guaranteed by the Constitution. In conclusion, Justice Douglas asserted that since there was no evidence of any harm caused by Lovejoy's actions or intent to cause harm on his part, his conviction should be reversed as unconstitutional.