SDCL § 23A-10A-1: Definition of mental incompetency.

The term, "mentally incompetent to proceed," as used in this chapter, means the condition of a person who is suffering from a mental disease, developmental disability, as defined in § 27B-1-18, or psychological, physiological, or etiological condition rendering him mentally incompetent to the extent that he is unable to understand the nature and consequences of the proceedings against him or to assist properly in his defense.

Source: SL 1978, ch 175, § 2; SDCL Supp, § 23-38-1.1; SL 1985, ch 192, § 47; SL 1991, ch 199, § 1.