None, although some have a &quot;duty to retreat&quot; which might come into play, especially in after the fact 20&#x2F;20 hindsight trials where the prosecutor ignores the dictum of Justice Oliver Wendell Holmes that “Detached reflection cannot be demanded in the presence of an uplifted knife.&quot;<p>In various parts of e.g. Europe, though, that would get you a prison sentence, very notably the U.K., since you would be using more force than the aggressor.  The US principle is that once the threshold of lethal force is reached, other forms of lethal force in response are legitimate.