Yes the act was a little extreme, but in the end it was justified. The Jedi attempted an illegal coup against the legal head of state of the Republic just because of his religion. To make that even worse Windu was going to kill the guy without a trial just because "he's to dangerous" and mainly because of his religion.
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Edited by RazorRyan: 6/28/2013 8:42:25 PMHe was a sith lord. It would have been one thing if he was just a simple apprentice but he was the lord of what was left of the sith empire. The Jedi couldn't have let him live. On top of that, he was in office longer than he should have been. The counsel let him have emergency powers because of the war, but since the war ended and he didn't step down well i guess it was acceptable to put him down.