SDCL § 53-4-7: Undue influence, acts constituting.

Undue influence consists:

(1) In the use, by one in whom a confidence is reposed by another, or who holds a real or apparent authority over him, of such confidence or authority for the purpose of obtaining an unfair advantage over him; or

(2) In taking an unfair advantage of another's weakness of mind; or

(3) In taking a grossly oppressive and unfair advantage of another's necessities or distress.