SDCL § 37-6-11: Mark similar to previously used marks not registrable.

A mark by which the goods or services of any applicant for registration may be distinguished from the goods of others shall not be registered if it consists of or comprises a mark which so resembles a mark registered in this state or a mark or trade name previously used in this state by another and not abandoned, as to be likely, when applied to the goods or services of the applicant, to cause confusion or mistake or to deceive.