Interesting, if other countries have less driving accidents then it may be worth considering lowering our legal limit. That is, if we can actually detect something is affecting them. Unless the driver is already driving erratically then we must presume the effects of any drink or other drugs isn't affecting them. Mandatory testing or randomly pulling people over to test them would be a gross over-reach. We trust people to change their own break pads, I trust them to know if they can drive on painkillers.