These are legal systems that are based on judicial decisions rather than written statutes. They are prevalent in countries that were influenced by British rule, such as the United States, the United Kingdom, Canada, Australia, and India. Common law systems rely on the doctrine of precedent, which means that courts follow the rulings of previous cases that are similar to the current one. Common law systems are also adversarial, which means that each side presents its own evidence and arguments to persuade the judge or jury.