“Street law” is not a kind of law. In other words, we do not talk about civil law, criminal law, and street law. Instead, Street Law is an organization that tries to teach people about law. The Street Law organization publishes a popular high school textbook entitled Street Law: A Course in Practical Law.
In its educational efforts, Street Law emphasizes practical law. It tries to teach people about the aspects of law that could or will be important to them in their normal lives. In other words, it is called “Street Law” because it wants to teach people about aspects of law that they could use “on the street.” It teaches them about things like criminal law and civil law. It also teaches them about the rights that they have under the Bill of Rights. Street Law does this because it believes that educating young people about the law and their legal rights will allow them to become better members of society. The organization (which is a non-profit) believes that it is helping to improve American democracy through its efforts.
Street Law, then, is an organization that puts out a textbook and engages in other efforts to educate Americans about the law and their legal rights.