Laws tell us what we must do and what we must not do. Laws always tell us what the punishment will be if we do not do as we should. Laws are written down in Acts of Parliament - called statute law. A second type of law is known as common law.  Common law is made up of rules that have been made by the courts when they have dealt with cases. It is what the judges have decided. It has the same authority or power as do those laws created by statute.