It will almost alwys be a he said/she said deal. But, laws like this call attention to the issue. According to the articles referenced below Colorado's law takes affect in August.


On the good side, sometimes other motorists come forward as witnesses:
http://www.dailycamera.com/news/2009...ation-cyclist/

On the bad side....sometimes other motorists want to take it even further....
http://www.dailycamera.com/news/2009...nrise-century/