S.D. Codified Laws § 23A-27-35
A sentence of imprisonment in a state correctional facility for any term suspends the right of the person so sentenced to hold public office, to become a candidate for public office, and to serve on a jury. Any such person so sentenced forfeits all public offices and all private trusts, authority, or power during the term of such imprisonment. Any person who is serving a term in any state correctional facility shall be a competent witness in any action now pending or hereafter commenced in the courts of this state, and the person's deposition may be taken in the same manner prescribed by statute or rule relating to taking of depositions. After a suspension of sentence pursuant to § 23A-27-18, upon the termination of the time of the original sentence or the time extended by order of the court, a defendant's rights withheld by this section are restored. However, the voting rights of any person sentenced to imprisonment in a state correctional facility shall be governed by Title 12.
SDCL 23A-27-35