United States v. O'Brien, 391 U.S. 367 (1968), was a landmark decision of the US Supreme Court ruling that a criminal prohibition against burning a draft card did not violate the First Amendment's guarantee of free speech. Though the court recognized that O'Brien's conduct was expressive as a protest against the Vietnam War, it considered the law justified by a significant government interest unrelated to the suppression of speech and was tailored towards that end. O'Brien upheld the government's power to prosecute what was becoming a pervasive method of anti-war protest. Its more significant legacy, however, was its application of a new constitutional standard. The test articulated in O'Brien has been subsequently used by the court to analyze whether laws that have the effect of regulating speech, though are ostensibly neutral towards the content of that speech, violate the First Amendment. Though the O'Brien test has rarely invalidated laws that the court has found to be "content neutral", it has given those engaging in expressive conduct—from wearing of black armbands to burning of flags— an additional tool to invoke against prohibitions. Background of the case Draft cards under the Selective Service Act In 1948, the United States instituted a peace-time draft with the Universal Military Training and Service Act (also called the Selective Service Act), which required all male American citizens to register with a local draft board upon reaching the age of 18. In 1965, Congress amended the act to prohibit the willful destruction of "draft cards" or registration certificates. These were small white cards bearing the registrant's identifying information, the date and place of registration, and his Selective Service number, which indicated his state of registration, local board, birth year, and his chronological position in the local board's classification record. The act had already required all eligible men to carry the certificate at all times, and prohibited alterations that would perpetrate a forgery or fraud. The 1965 amendment, however, made it a separate crime under 50 U.S.C. § 462(b)(3) to "knowingly destroy" or "knowingly mutilate" the card. This amendment was passed at a time when public burnings of draft cards to protest the Vietnam War were a growing phenomenon, many observers (including the U.S. Court of Appeals for the First Circuit) believed that Congress had intentionally targeted such protesters. O'Brien's protest and conviction On the morning of March 31, 1966, David Paul O'Brien and three companions burned their