Yes.
It's very true that, when we look at the effects of a particular measure like mandatory breath testing, changes to legal limits, or RIDE programs, there are other things that need to happen.
I've said that legal limits and per se laws are important to introduce, but we also need education. If you passed a law and nobody knew about it, that really wouldn't have the effect you want it to have. I think you're correct that other things need to happen for mandatory breath testing to work as well as it can.
We have a colleague who's a criminologist in Australia, Ross Homel, who wrote a chapter for a book comparing the different experiences in the different states. He pointed out that some states really introduced it in a half-hearted fashion and there wasn't much testing that happened. Other states were what he called “boots and all”; I guess that's an Australian term. That's where you saw the biggest effect; it was where they had large numbers of people being tested and lots of education. From a general deterrence perspective you saw that the average person—you and I—would think, “Gosh, my chances of being detected are really high.” He clearly makes the point, and I would agree with you that you need all of these other pieces to achieve the kind of success that you can achieve with a measure like mandatory breath testing.