In an amendment sponsored by Congressmen L. Mendel Rivers and William G. Bray, on August 31, 1965, the law was augmented with four words, to include penalties for any person who ''knowingly destroys, knowingly mutilates'' the card, under 50 U.S.C. 462(b)(3). Strom Thurmond moved the bill through the Senate, calling draft-card burning ''contumacious conduct'' which ''represents a potential threat to the exercise of the power to raise and support armies.'' At the time, many observers (including the U.S. Court of Appeals for the First Circuit) believed that Congress had intentionally targeted anti-war draft-card burners.

What's the best answer to this question: is it illegal to burn a draft card?
yes