William Allen of Michigan State University ties them together here.
We define civil rights in the context of the founding of the United States Constitution, and in many respects they are best understood in that light. The first place in which to find that context is the Declaration of Independence, which declares the meaning of civil rights. Secondly, we have the best indigenous articulation of civil rights from that founding father who also best explained the relation between civil rights and natural law: James Wilson. Thirdly, reviewing illustrative Supreme Court defenses of civil rights can quickly reveal how far the decisions of the justices were regulated so as to tie advances in civil rights to an advance in understanding natural law (even for persons who would disavow reliance upon natural law). Finally, the seminal statement of Dr. Martin Luther King, Jr. in his “Letter from a Birmingham Jail,” clearly expresses the fundamental ground of equality identified by James Wilson (and the Declaration of Independence) as essential to civil rights; it also invokes the entire sweep of Western reflection on the meaning of justice in such a way as to show the pursuit of civil rights as nothing less than perfecting civil relations in light of natural law.