Mo. Rev. Stat. § 537.085: Defenses to wrongful death action.

On the trial of such action to recover damages for causing death, the defendant may plead and prove as a defense any defense which the defendant would have had against the deceased in an action based upon the same act, conduct, occurrence, transaction, or circumstance which caused the death of the deceased, and which action for damages the deceased would have been entitled to bring had death not ensued.