I think we all know what’s the only foolproof solution here is: anal probe. It would be integrated into driver’s seat and make a measurement every couple minutes. Yes, I know, it could be defeated by sitting on sober person’s lap while you drive but I don’t actually think it’s a big security issue. If you have someone who can sit in driver’s seat the whole trip they can probably also drive. Also it would be very uncomfortable for everyone and very easy to spot by police. Any other solution is stupid and wouldn’t work. It’s so obvious I don’t think it even merits a serious discussion. Anal probe is the only way: it doesn’t depend on some shitty AI face recognition BS that will fail randomly or won’t work at all for some people, you can’t cheat it by having someone else start your car, you can’t cheat it by having the passenger blow into something or give his blood sample and it’s compatible with every driver