私法，相对于公法，一般而言指的是规范私权关系的法律。

目前区分公、私法并未有一个统一的标准理论，但比较多数人采的是所谓的「新主体说」，这一个说法的区分标准是：如果一个法律关系中，出现的法律主体其中一方是以公权力姿态出现的国家主体，那么适用在这个法律关系中的法律，就是公法；反之，如果双方没有出现这样的主体，就是私法。

举例来说：台北市政府向池上便当订购饭盒， 这里台北市政府出现的姿态，和公权力无关．

必须注意的是，新主体说是用来区分「法律」本身的定性，而「法律关系」是公法关系或者私法关系，则是另一件事情。

Private law is that part of a civil law legal system which is part of the jus commune that involves relationships between individuals, such as the law of contracts or torts (as it is called in the common law), and the law of obligations (as it is called in civil legal systems). It is to be distinguished from public law, which deals with relationships between both natural and artificial persons (i.e., organizations) and the state, including regulatory statutes, penal law and other law that affects the public order. In general terms, private law involves interactions between private citizens, whereas public law involves interrelations between the state and the general population.