They use a lot of video enforcement in the U.S., and they do a lot of training. It's important that law enforcement be trained, because you want to make sure, when the video gets to court, that people know what they're looking at, so that they can hear that the person was mumbling or couldn't talk properly, or see them falling down and that the lighting is good. They've had a lot of success with video at roadside and at booking in proving the impairment.
On February 7th, 2008. See this statement in context.