Gilbert,
Obviously your training in the law department is nil. Mine is also zero. However, there is a minimum that one should know about the law and, believe me, it includes entering a plea. By entering a "non-guilty" plea, one gets a court trial. Remember that the court considers you innocent until proved guilty beyond a reasonable doubt. This means that the prosecutor must give evidence to the court to prove beyond a reasonable doubt you are guilty of the offence. It also gives you a chance for a plea bargaining to a lesser charge, which works most of the time.
In the case of al-Zaidi, his lawyers advised him to plead "non-guilty" to the charge of "attempting to assault a visiting head of state." They were hoping to convince the court to reduce the charge to "insulting a visiting head of state," which was more appropriate, but they failed. However, the case was so politically charged, with the Americans pushing behind, I believe he is lucky to have gotten away with only three years: I thought he would get "life."
I am sure that you will have noticed that on the other hand, many US soldiers have gotten away for murdering in cold blood Iraqi civilians, men, women, and children, and their punishments have only been a dishonorable discharge. So, three years for throwing a SMD that's a little over the top!?
al-Zaidi is a hero in the sense that he had the cojones to do what millions would have wished to do, but did not have the opportunity or the guts to do it. I am sure that it was not premeditated. It was on the spur of the moment, when an uncontrollable hate took him over, as he thought of the estimated million of his fellow Iraqis who had been killed thanks to the mass-murderer, Bush, standing in front of him, apparently very proud of himself for all the misery he had brought to Iraq.
However, I must retract my calling him a "hero," as I think I got a little carried away on that one: the word "hero" has seriously been devalued recently, and I don't want to be contributing to it. But I am VERY impressed by his courage and convictions. If I had been in his shoes (no pun intended), I wonder if I would have had the guts to do the same thing, for two reasons:
1) Although I sympathize with the Iraqi people rising against the invaders, I am not an Iraqi, and
2) I am a coward.
Anyway, it's just a matter of perspective, and he is certainly a hero to many millions of people throughout the Middle East.
As for the American soldiers in Iraq being heroes, please, don't get me started on this one…

Keep on smiling.
Daniel
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"War is terrorism on a bigger budget."