When the story of a student being tazed at a John Kerry speech was presented on the media it looked like an example of the crushing of free speech that the left accuses the US administration (and the government here in Australia, as well) of doing.
When you see the full video, it's a different story. You should also know that they guy being tazed has a website on which he shows videos of himself at public events generally making an ass of himself by making idiot statements. He takes with him someone to video him and, in this example, checks that he's being recorded before beginning his verbal diarrhoea.
He won't give up the microphone after his allowed two minutes and makes a statement that John Kerry had two hours so he should have more time. Leaving aside the possibility that his mind may have atrophied after listening to Kerry for two hours and may not have been in full control of his faculties it seems tremendously narcissistic to think that you're as important as the US Senator that people have actually come to listen to.
Having had the microphone turned off, he then starts shouting and when the police move in to remove him the crowd cheers and claps. He continues to resist and gets tazed, which may well have been an over the top response but it's hardly an example of crushing of free speech.