Common Law

Another type of law is called common law. Common law refers to rules that are developed over time by the courts instead of created by the legislative or executive branch. These court rulings are based on centuries of social customs. For example, suppose you have a broken set of steps leading to your front door, and someone is injured as they try to knock on your door. You can be sued for negligence and forced to pay for the person's medical treatment even though there is no statute or written law against having broken steps. The court would say that, as a homeowner, you're responsible for hazardous conditions on your property. The court would be using the common law to decide the case rather than a specific statute passed by the legislature. 

When one person does something that causes harm to another person, the person who was harmed might sue to receive compensation for the harm caused. For example, most states don't have a specific law prohibiting you from taking and publishing a photo of someone who is sleeping in a hospital bed. But if you do take and publish such a photo, the person might sue you for invasion of privacy. You haven't violated any specific law, but you still might be forced to pay damages for the harm you caused (emotional distress and embarrassment).

Courts have heard many cases related to invasion of privacy. Over time, all these court decisions become unwritten rules. Let's say that 30 years ago a court considered a case where someone published a photo of a woman giving birth. At the time, the court said that this was an invasion of the mother's privacy, and the photo shouldn't have been published without her permission. Maybe 5 years later there was a case where a man sued after a photo was published of him having surgery, and he also won his case. A few years later, a woman won her suit when a photo was published of her wearing a hospital gown. Now we have three different cases where the court decided that publishing a photo of a person in the hospital was an invasion of privacy. In future cases, the court will try to apply the same logic and rule based on these previous decisions (Figure 1.2 illustrates this idea). This is how the common law develops. The common law gives the judicial system a way to deal with cases where there is no written rule but there is a dispute between private individuals.