Marshall had to consider the definition of treason and whether intent was sufficient for conviction, rather than action. Marshall ruled that because Burr had not committed an act of war, he could not be found guilty (see "Ex parte Bollman"); the First Amendment guaranteed Burr the right to voice opposition to the government. To merely suggest war or to engage in a conspiracy was not enough. To be convicted of treason, Marshall ruled, an overt act of participation must be proven with evidence. Intention to divide the union was not an overt act: "There must be an actual assembling of men for the treasonable purpose, to constitute a levying of war." Marshall further supported his decision by indicating that the Constitution stated that two witnesses must see the same overt act against the country. Marshall narrowly construed the definition of treason provided in Article III of the Constitution; he noted that the prosecution had failed to prove that Burr had committed an "overt act," as the Constitution required. As a result, the jury acquitted the defendant.