I don't think that checkstops are that big a deterrent at all. They may stop some of the borderline drivers but those people are likely the least dangerous of all the drivers and very unlikely to drive in a dangerous state anyways.
I think the biggest deterrent is for lack of a better term morality/safety/social concerns that people have.
If people have no qualms about driving drunk I doubt that they are that concerned about the very, very small chance of running into a checkstop.
|