It is justifiable to use force or violence or to kill in the defense of another person when it is reasonably apparent that the person attacked could have justifiably used such means himself, and when it is reasonably believed that such intervention is necessary to protect the other person.
La. R.S. 14:22
Defense of others
Known as the Louisiana Criminal Code
The act spans §§ 14-1 to 14-9 (36 sections).
Official source: Louisiana State Legislature. Reproduced from public-domain Louisiana statutes; confirm against the official source for the current text. Not legal advice.