Systems like Tesla Autopilot, GM’s Super Cruise, and Nissan’s ProPilot Assist can automatically follow traffic and even drive hands-free on highways but need drivers to be ready to take over from the supposedly smart software at any moment. To guarantee drivers aren’t napping, Snapchatting, or Candy Crushing when they’re using these advanced driver-assistance features, automakers have rolled out a second layer of technology called driver-monitoring systems. Their job is to look for signs that a human—notoriously unpredictable as they are—is indeed ready to take over when those limited automated-driving features get out of their depth.

Driver-monitoring systems are making their way into vehicles not just because automakers need them to enable automated wizardry but because they’re facing increasing pressure from regulators and safety groups in Europe and the US.

All new car models sold in Europe will have to have driver-monitoring systems by mid-decade, even if they don’t come with partially automated features.