You can this side of the pond. There are two defence's to an action for liable. One is "fair comment" and the second is that you are telling the truth. Newspapers tend to rely upon the first defence. As for the Congress Critter, it's normal for parliments to have quite extensive privilege with regards to what their members can say. How far the CC can go, depends entirely on the Speaker.
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I don't do dumb & helpless.