There's also one caveat, SOME jurisdictions allow people who honestly believe that another is in danger of serious bodily harm to intervene with deadly force. Other jurisdictions require one to be correct in believing someone else is in threat of serious bodily harm.
The example being, two guys fighting, one pulls out a gun and you SWEAR he's about to shoot the other, so you intervene. Normally that would exonerate guilt. On the other hand, what if the man who pulled out the gun was an undercover cop, or was defending himself from a knife robbery?. What then?
Just a nuanced consideration when deciding to intervene. Hope I helped explain some.