If you own a gun, understanding self-defense law is an absolute requirement.
Consider this:
You and your spouse are enjoying a day shopping at the mall. Everything is on sale, so you are going a little crazy buying all sorts of stuff. Both of you have your arms full of bags loaded with your newly purchased goodies so you leave, exiting to the parking lot. As you are walking through the parking lot you hear a ruckus from behind a van. You carefully put your bundles down behind your two-week old mid-sized SUV and proceed to investigate the activities on the other side of the van.
Ordinarily, you would just drive away and maybe call 911, however you are armed, and invincible. (After all you have a License to Carry and took a course where you shot 2 different guns, so you are good to go.) Now it sounds like a woman is being abused (muffled screams). As you poke your nose around the corner of the van, you see two large men trying to subdue a woman who appears to be fighting for her life and giving those two brutes more than they can handle. The men are yelling and cursing telling her to stop struggling while working to get her on the ground.
It is definitely hero time! You draw your new Ruger American Pistol, chambered in 9 mm Speer hollow points and take a good Weaver stance, which you read about in a guns magazine, get a good two handed grip on the gun and point it at those two ruffians and yell: “Stop, I am an armed citizen and will shoot you if you do not let her go.” You are feeling good when all activity stops but they don’t let go of the woman. One of the men tells you to shut up, go away or else, at least that is what you thought he said. You think: “I have a gun and I am in charge here”. Now you are angry and yell: “Let her go NOW or I will shoot.” One of the men starts to say something but you are ready and point you gun right at his face and say: “Open your mouth again and I will fill it with lead”. (Sounds like something Dirty Harry would say so you are feeling very cool.)
The ruffians get the message and let the girl go. You instruct them to get on their knees and put their hands on their heads, interlocking their fingers. (Learned that one from watching Adam 12.) You tell the woman to come over to you where it is safe, but she unexpectedly runs away as fast as she can go. You attribute her behavior to the fact that she was just terrified, and she is just following her flight reflex. You are the hero, even if she is not there to express her eternal gratitude.
What happens next?
You are arrested and go to jail and you cannot use the affirmative defense of self-defense/defense of others. Why not?
If you own a gun, understanding self-defense law is an absolute requirement
What could possibly have gone wrong? Things are not always as they appear.
You came upon a situation where you made assumptions as to who was doing what to whom. A young lady being subdued by two ruffians. Or was it a woman criminal being arrested by two undercover police officers. Yup, it was a legitimate arrest being performed by two police officers and you assisted the criminal to escape custody, making you potentially an accessory to her crimes and certainly guilty of interfering with law officers in the legal course of their duties. Hopefully the prison has a good library.