The founding fathers would have treated flag-burning as free speech

The Framers were working within a late 18th century common-law legal system that generally treated symbolic expression and verbal expression the same. Speech restrictions — such as libel, slander, sedition, obscenity and blasphemy — covered symbolic expression on the same terms as verbal expression…

Protection of symbolic speech would have fit well with James Madison’s initial draft of the First Amendment, which spoke of the people’s “right to speak, to write, or to publish their sentiments.” Courts and commentators (including early Supreme Court Justice James Wilson) routinely used “publish” to refer to publicly displaying pictures and symbols, as well as printing books. When Congress recast Madison’s phrasing to the shorter “freedom of speech, or of the press” it was not seen as a substantive change.

The three most influential early writers on American law — St. George Tucker, Chancellor James Kent and Justice Joseph Story — all expressly characterized the First Amendment as protecting a right to speak, to write, and to publish.

To be sure, some in the Founding era took a narrow view of free speech. They would have allowed the punishment — probably as “sedition” — of stridently antigovernment sentiments, likely including those conveyed by burning the flag. But they would not have denied that the First Amendment protects symbolic expression generally. They would have just argued that both harshly antigovernment symbols and harshly antigovernment words were punishable.