You look down at your phone for two seconds to check a text message. At 55 miles per hour, your car travels the length of a football field in that time. You rear-end the car that stopped in front of you. The driver’s neck is injured. Your insurance premiums go up. You might think that’s the end of it. It’s not. That two-second glance just opened you up to a civil lawsuit for negligence.

Negligence is the legal foundation for most personal injury claims based on distracted or careless behavior. The law does not require you to be intentionally reckless. It only requires that you failed to act as a reasonably careful person would under the same circumstances. When you pick up a phone while driving, you fail that test almost every time.

The legal system uses a four-part test to determine negligence. First, you had a duty of care. Every driver owes a duty to other people on the road to operate their vehicle safely. Second, you breached that duty. Picking up your phone, reading a text, or programming a GPS while the car is moving is a clear breach. Third, your breach caused the accident. If you crashed because you were distracted, the “but for” test applies: but for your distraction, the accident would not have happened. Fourth, the other person suffered actual damages. Medical bills, lost wages, pain and suffering, property damage. All four elements must be present. In distracted driving cases, they almost always are.

Smartphone use is the most common form of distracted driving, but it is far from the only one. Eating, adjusting the radio, talking to passengers, grooming, and reaching for objects all qualify. The legal question is not whether you intended to cause harm, but whether you chose to engage in an activity that made you less attentive. Courts repeatedly find that any voluntary act that takes your eyes, hands, or mind away from driving is a breach of the duty of care.

One nuance that many non-lawyers miss is the concept of comparative fault. If you are the distracted driver, you might try to argue that the other driver was also careless. Perhaps the person you hit was speeding or failed to signal. In many states, the jury assigns a percentage of fault to each party. If you are found 80 percent at fault and the other driver is 20 percent at fault, your liability is reduced by that 20 percent. But here is the hard truth: a distracted driver who rear-ends someone is almost always assigned the majority of fault. Following too closely and failing to pay attention are nearly impossible to overcome in court.

The damages in a distracted driving case can be substantial. Medical bills for a simple whiplash injury can run into the tens of thousands of dollars. More serious injuries, such as traumatic brain injury or spinal cord damage, can result in lifetime medical care costs in the millions. Pain and suffering damages are calculated differently by each state, but they often multiply the economic damages by a factor based on the severity of the injury. Your insurance policy limits may not cover the full amount. If the damages exceed your coverage, the injured party can come after your personal assets. Your savings, your home, your future wages could be at risk.

There is also the possibility of punitive damages. These are not about compensating the victim. They are about punishing you for particularly egregious behavior. If you were texting repeatedly, watching a video, or scrolling through social media at the time of the crash, a jury may decide that your conduct was so reckless that it deserves additional punishment. Punitive damages are not covered by insurance in many states. You pay them out of pocket.

The law does not care that you are a careful driver most of the time. It does not care that you only checked your phone for a second. It does not care that you thought you could handle it. The law looks at the objective facts. You chose to engage in a distracting behavior. That choice caused harm. You are liable.

The best way to avoid this legal liability is simple. Put the phone away. Use hands-free features only for essential navigation, and even then, set your destination before you start moving. Pull over if you need to make a call or send a text. No message, no song, no GPS instruction is worth the legal and financial consequences of a negligence lawsuit.

If you are already facing a lawsuit for distracted driving, do not try to handle it yourself. Hire a lawyer immediately. Do not talk to the other party’s insurance company without representation. Do not post anything on social media about the accident. Anything you say can be used to prove that you were distracted. The law is unforgiving. The best defense is to have never been distracted in the first place.