Comment and brilliant reply in WP comments to story about Rep. Stuebe falling 25' out of his tree:

"What exactly "knocked" the congressman?

More than likely, after cutting a limb, that limb fell and knocked him off the ladder...
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Reply:
While technically correct, I think you're missing the point: Saying he was "knocked off" by a limb he cut himself is like saying a car piloted by a drunk was "struck by a guardrail."