Don't permit any. If it lasts for days, don't drive for days.
You don't get to use the excuses of "The 15 drinks I had remained in my bloodstream for hours" or "It's unclear whether it was the 0.2 alcohol level because there's also evidence of marijuana and other drugs in my body."
I believe in Colorado if it’s discovered in your car. You are automatically considered to be out.
I hdave no problem with that. Really getting tired of Walt the postman being criminalized for smoking a Dookie. On the weekends.