It has long been recognized by the courts that not only written and spoken words," but certain acts and conduct will likewise be considered a form of speech protected under the First Amendment. However, it has been difficult for the courts to determine exactly what type of conduct or action is acceptable and thus protected as "symbolic" speech,and those which are objectionable in that they contravene public policy. This exact difficulty arose in two of the present cases. The Miller Court found that it could not determine whether willful burning of a draft card was speech; nevertheless it was punishable. In O'Brien, the Court said it was speech, but still punishable.
Robert M. Phillips, Draft Card Burning, 18 Clev.-Marshall L. Rev. 407 (1969)