SDCL § 43-3-18: Future interest unaffected by act of owner of intermediate or precedent interest.

No future interest can be defeated or barred by any alienation or other act of the owner of the intermediate or precedent interest, nor by any destruction of such precedent interest by forfeiture, surrender, merger, or otherwise, except as provided by § 43-3-19, or where a forfeiture is imposed by statute as a penalty for the violation thereof.