15 GCA § 811: Collateral Consanguinity Defined.

Collateral consanguinity is the relationship between people who spring from a common ancestor, but are not in a direct line. The degree is established by counting the generations from one relative up to the common ancestor and from the common ancestor down to the other relative. In such computation the first relative is excluded, the other included, and the common ancestor counted but once. Thus, brothers are related in the second degree, aunt and niece in the third degree, first cousins (also known as cousins german) in the fourth degree, and so on.