Published April 16, 2024 · Injury Law Basics

The driver who rear-ended you on I-675 says he did not do anything wrong. His car has adaptive cruise control and lane-keeping. "It was supposed to brake," he tells the officer. "The car didn't see you."

More and more vehicles on Dayton-area roads come with driver-assistance features: adaptive cruise control that keeps a set distance from the car ahead, lane-centering that steers within the lines, automatic emergency braking, and blind-spot warnings. These systems can prevent crashes. But when one is involved in a crash, the at-fault driver and the insurance company may try to use the technology as an excuse. Under Ohio law, it usually is not one.

What these systems are, and what they are not

The features sold today on ordinary passenger cars are driver assistance systems. They help with steering, speed or braking in certain conditions, but they are designed to work with a driver who is watching the road, holding or ready to take the wheel, and prepared to take over at any moment. The automotive industry commonly describes these as partial automation, a level at which the human driver remains responsible for monitoring the road at all times. Owner's manuals typically say much the same thing.

None of that changes when a driver chooses to trust the system more than he should. A car that can hold its lane on the highway is not a car that drives itself.

The driver is still the driver under Ohio law

Ohio's traffic laws are written for people, and they do not carve out an exception for drivers who hand control to software.

  • Reasonable control. R.C. 4511.202(A) prohibits operating a motor vehicle on a public road "without being in reasonable control" of it. A driver reading a phone while lane-centering steers is not in reasonable control.
  • Assured clear distance ahead. R.C. 4511.21(A) requires drivers to travel at a reasonable speed and to be able to stop within the assured clear distance ahead. If adaptive cruise fails to slow for stopped traffic, the driver who was supposed to be watching still had the duty to stop.
  • Ordinary negligence. Beyond specific statutes, every driver owes others the duty of reasonable care. Over-reliance on an assistance feature, ignoring the system's own warnings to take the wheel, or using a feature in conditions it was not built for (heavy rain, construction zones, city streets) are all evidence of carelessness.

In practical terms, a crash involving a driver-assist vehicle is analyzed the same way as any other crash: what did the driver do, what should the driver have done, and did the failure cause your injuries. Our page on rear-end collisions, where these systems most often come up, explains how fault is proven.

When the manufacturer may share the blame

Sometimes the technology really is part of the problem. A system may brake suddenly for no reason ("phantom braking") and cause a following driver to crash. It may fail to detect a stopped vehicle, a motorcycle, or a pedestrian in conditions it was marketed to handle. It may let a driver keep it engaged long after the driver's hands have left the wheel.

Ohio's Product Liability Act gives an injured person a claim against a manufacturer whose product was defective. Under R.C. 2307.73(A), the injured person must prove that the product was defective in one of four ways (in manufacture, in design, because of inadequate warnings or instructions, or because it did not conform to the manufacturer's representations) and that the defect was a proximate cause of the harm.

That can matter a great deal in a serious case:

  • A second responsible party. The at-fault driver may carry only minimum insurance. A manufacturer is a defendant with the resources to pay a full judgment.
  • Warnings and marketing. How a feature was named, advertised and explained to drivers can bear on whether the warnings were adequate.
  • Both claims together. The driver's negligence and the product's defect are not mutually exclusive. Ohio's comparative-fault rules allow fault to be allocated among everyone responsible. Our guide chapter on what your case is worth explains how that allocation affects recovery.

Product cases are expensive and technical, and they require engineering experts. Not every crash involving driver assistance supports one. But the possibility should be evaluated early, because the evidence disappears fast.

The data that decides these cases

Modern vehicles record a remarkable amount of information. The event data recorder, or "black box," typically captures speed, braking, throttle and seat-belt use in the seconds around a crash. Many vehicles with driver-assistance features also log whether a system was engaged, whether it issued warnings, and whether the driver's hands were detected on the wheel. Some manufacturers collect data remotely through the vehicle's connected services.

All of that can prove what the driver was doing, or what the car was doing, at the moment of impact. And all of it can be lost: a totaled vehicle is often sent to auction within weeks, and remotely collected data is held under the manufacturer's own retention practices.

Ohio law recognizes the problem. If a product is destroyed, R.C. 2307.73(B) allows a defect to be proven with circumstantial evidence, but direct evidence is always better. That is why, in a serious crash involving driver-assistance technology, we send written preservation demands to the other driver, the insurers, the tow and salvage yards, and when appropriate the manufacturer. Our guide chapter on gathering evidence while it still exists explains how preservation letters work.

We discussed related issues last year in our post on electric-vehicle crashes and battery fires. The theme is the same: new technology, same Ohio liability rules, and a premium on getting to the evidence first.

What this means for you

If the driver who hit you blames the car:

  • Do not accept the excuse. The driver remains responsible under Ohio law.
  • Write down what the driver said at the scene, including any mention of autopilot, cruise control or lane assist. Tell the officer.
  • Keep your own vehicle and its data until your lawyer says otherwise, especially if it was totaled.
  • Do not give a recorded statement to the other driver's insurer.
  • Call a lawyer quickly so that preservation demands go out before the vehicles and data are gone.

We handle car and truck crash cases across the Miami Valley, including cases involving vehicle technology and defective products.

This article is general information about Ohio law, not legal advice about your situation. Reading it does not create an attorney-client relationship. Deadlines and rules change; talk to a lawyer about your specific case.