It may be a poor proxy, but it's better than nothing. The evidence we've heard is that the field sobriety tests are also, particularly for cannabis, not particularly effective. We have to do something. Maybe it's a poor proxy, but isn't it far better than nothing? What's the alternative? Is it on field sobriety tests that we would land as the only thing we would do?
On September 25th, 2017. See this statement in context.