Why Mandatory Ignition Interlocks Could Backfire on Drivers

Wouter Smit · 2026-07-25

Mandating automakers to install ignition interlock devices in every new vehicle sounds like a no-brainer on paper. Fewer drunk drivers on the road? Who could argue with that? But once you start digging into the practical side of things, the picture gets a lot murkier. It's one of those ideas that looks great in a press release but starts to crack when you think about real people, real cars, and real life. ### The Theory Sounds Great Here's the pitch: every car comes with a built-in breathalyzer. You blow, the car starts, and everyone's safer. It's a simple, clean solution that would theoretically prevent thousands of DUI-related deaths every year. In fact, the National Highway Traffic Safety Administration has studied this exact concept for years, and the data on interlock effectiveness is genuinely impressive. When they're used by convicted offenders, these devices reduce repeat offenses by roughly 70 percent. That's a massive win. And it's why advocacy groups keep pushing for broader adoption. But there's a huge gap between requiring interlocks for people who've already been caught and building them into every single car that rolls off the assembly line. That gap is where the trouble starts. ### The Practical Nightmares Let's talk about what a mandatory interlock actually means for you. First, there's the cost. These devices aren't cheap. You're looking at installation fees around $100 plus monthly calibration and monitoring costs that can run anywhere from $60 to $80. Over a year, that's easily over $1,000. Now imagine that bill hitting every new car owner in America, whether they've ever touched a drink or not. That's a regressive tax on transportation, and it hits lower-income families the hardest. Then there's the false positive problem. The sensors in these devices are sensitive. Things like mouthwash, certain medications, or even a fresh piece of bread with yeast can trigger a reading. You could be completely sober and still get locked out of your own car at 7 AM on your way to work. Manufacturers have tried to mitigate this with cameras and pressure sensors, but the technology still isn't perfect. ### The Privacy and Reliability Questions Here's another angle that doesn't get enough attention: data privacy. Every time you blow into one of these devices, it logs a reading. That data gets transmitted to a monitoring service. If interlocks become mandatory, automakers and third-party vendors would collect biometric and behavioral data on millions of people who haven't done anything wrong. Who owns that data? Who can access it? What happens if it gets hacked? These aren't hypothetical questions. There's also the reliability issue. These devices need regular calibration, usually every 30 to 60 days. That means a mandatory trip to a service center. For someone living in a rural area, that could be a 50-mile round trip just to keep their car running. And if you skip a calibration appointment, the device can actually lock you out, leaving you stranded with a car that won't start. ### The Unintended Consequences When you push people into a corner, they find workarounds. If every car has an interlock, you'll see a black market for "start bypass" services. People will find ways to defeat the system, and that's not just a legal problem; it's a safety problem. The people most likely to circumvent the technology are the exact people it's designed to stop. ### A Better Path Forward None of this means ignition interlocks are bad. They're a proven tool when used as a punishment for offenders. The smart move is to keep them there and expand their use through court orders, not to bake them into every vehicle. Let's focus on making the devices cheaper, more accurate, and more privacy-friendly first. Then, maybe, we can have a real conversation about universal adoption. Until then, the theory stays ahead of the practice, and that's a dangerous place to be.