Does a theory of civil disobedience necessarily depend on there being a Natural Law?

Some of the most famous practitioners of civil disobedience, most notably Martin Luther King, Jr., have based their actions on their belief in a higher law, a moral code that superseded the laws of men. They claimed, as King wrote (quoting St. Augustine), that "an unjust law is no law at all." People were thus bound to "natural law," and could only obey actual laws to the extent that they conformed to it. Natural laws, of course, were understood to mean those established by God. While King, Gandhi, and others based their actions on natural law, a belief in this concept is not essential to civil disobedience. A person could refuse to obey a law because they judged that it did more harm to people than good. This would be something like a utilitarian perspective on civil disobedience. A person could also exercise civil disobedience in order to draw attention to a law they saw as ineffective or discriminatory. A belief in natural law is not essential to civil disobedience.
https://plato.stanford.edu/entries/natural-law-ethics/