Brown on trial, painting by David C Lithgow,
Essex County Historical Society,
Certainly John Brown was found guilty of treason by the State of Virginia. The legal rationale behind this charge was that even though Brown was not a Virginian, he could be guilty of treason because he had previously enjoyed the privileges and freedoms offered him by the state. So, as a U.S. citizen, he had an equal loyalty to the states of the union individually. Students are advised to read Brian McGinty's book, JOHN BROWN'S TRIAL. Of course, this argument is debatable and certainly was convenient to the pro-slavery side of the case. But there was some precedent in the U.S. constitution for this charge. A related issue is that John Brown invaded a federal facility on federal grounds in Virginia, and yet the President of the U.S. let Virginia prosecute Brown without involving federal jurisdiction. There were certainly politically pro-slavery reasons for this strategy.
Not clear about the second part of the question, "was his reason valid?" If the question actually was supposed to mean, "was this reason valid?" then perhaps what has been discussed so far should suffice in basic terms. Once again, students should read the McGinty book, which is the first extended study about Brown's trial and will probably be the definitive work for a long time.
But if the second part of the question pertains to John Brown's reasons for invading Virginia, then of course there is room for more discussion and debate.
To start with, a purely legalistic and typically conservative reading would conclude that Brown was wrong. People arguing from this position would say that laws are laws, and we are a nation of laws, and that violating the rule of law destroys the essence of the nation--therefore Brown must be judged first and last a criminal. But this view tends to be amoral, it is indifferent to human reality as well as the centrality of moral convictions, especially in a society like the U.S. whose founders made appeals to philosophy, politics, and theology.
Thus, if one puts laws above everything else, then any law that is passed remains sacrosanct, no matter how wrong or bad it is. This locks humans into a position of obeying laws put into place by unjust or immoral leaders, as has often happened in human history.
We must remember that in 1859, the law of the U.S. was in favor of chattel slavery. Most people today would find such a rule of law unconscionable: black people were not viewed as full humans, their bodies, families, labor, and self-determination were controlled by slave masters, the market, and the federal government. Slavery presumed stolen labor, the use of terror and violence to sustain slavery, and essentially required the entire nation to cooperate, free states included. The Fugitive Slave Laws, especially the one passed in 1850, made free states responsible for slavery to continue. So we have to let go the romanticized, sentimental view of "American history" and realize that our nation was a kind of fascist state as far as black people were concerned.
In light of the totality of slavery's corruption and violation of human rights (not to mention how it contradicted the very premise of the nation's founders--something that John Brown believed), simply arguing that "breaking the law makes John Brown wrong" is not so persuasive.
John Brown was trying to do something--actually do something--when the issue of slavery was still a matter of political compromise, give-and-take between white politicians in the North and South. Even Lincoln was willing to tolerate a limited slavery as long as it didn't spread to new territories.
John Brown did not want to kill slaveholders; he believed some measure of force would be necessary given the violence upon which slavery was founded. But his goal was to somewhat arm the underground railroad--it put the underground railroad idea more on the offensive and give it a measure of force. His goal was to panic and destroy the slave economy without broad scale bloodshed.
Lastly, if people are going to hold Brown to the very narrow view that "breaking the law" makes him a bad man, then they at least had better be consistent in their historical view of everyone else. By this reasoning, anyone who breaks laws is wrong, no matter what the circumstances. Of course, no one would hold to such a ludicrous position, particularly when a particular law touches their concerns in a negative fashion. If nothing else, John Brown was being consistently "American" by appealing to the higher moral and ethical arguments for black freedom based upon the precedent set by the founders. He consciously argued along these lines (i.e., that the real intention of the founders had been co-opted by slave holders); nor was he trying to overthrow the political structure of the U.S., except as it pertained to slavery.
Seen through the narrow, legalistic lens of the conservative, Brown is a lawbreaker and nothing more. But seen through a full scope that appreciates law but also closely examines political realities, moral arguments, and the real facts of John Brown's case, the weight of history's judgment will probably prove to be in Brown's favor. That he broke the laws of a nation committed to cruel, racist slavery actually is quite refreshing when we consider that most whites did nothing at all. Even Lincoln the lawyer defended the rights of slave holders, and as a new president, he was willing to compromise with slave masters in order to save the Union (which was always more important to Lincoln, even before he was the president). People who argue against Brown tend to overlook or even ignore the evil of slavery, and they seem to presume that life in the U.S. in 1859 was essentially fair and balanced. This is very problematic and it may also suggest a measure of hidden prejudice. In fact, the reason that Brown is probably as unpopular as he is among a segment of people in this nation is more a fact of longstanding prejudices and bigotry than about legality, "treason," or even political radicalism. [Submitted 22 Nov. 2010--LD]