Physical harm need not be intentionally caused. A pedestrian knocked over by an automobile does not hurt less because the driver intended no wrong but was merely careless. The law imposes a duty of care on all of us in our everyday lives. Accidents caused by negligence are actionable.
Determining negligence is not always easy. If a driver runs a red light, we can say that he is negligent because a driver must always be careful to ascertain whether the light is red and be able to stop if it is. Suppose that the driver was carrying a badly injured person to a nearby hospital and that after slowing down at an intersection, went through a red light, blowing his horn, whereupon a driver to his right, seeing him, drove into the intersection anyway and crashed into him. Must one always stop at a red light? Is proof that the light was red always proof of negligence? Usually, but not always: negligence is an abstract concept that must always be applied to concrete and often widely varying sets of circumstances. Whether someone was or was not negligent is almost always a question of fact for a jury to decide. Rarely is it a legal question that a judge can settle.
The tort of negligence has four elements: (1) a duty of due care that the defendant had, (2) the breach of the duty of due care, (3) connection between cause and injury, and (4) actual damage or loss. Even if a plaintiff can prove each of these aspects, the defendant may be able to show that the law excuses the conduct that is the basis for the tort claim. We examine each of these factors below.