Ver nice concise write up!OK, I will give Robert the benefit of the doubt.
As others have said, it is unlikely your defense would hold up. Once the threat is moving away from you, you are no longer justified in shooting. You would have moved from victim to offender.
You would have several options from the start of this situation:
1. Be aware of your surroundings. If someone looks or acts suspicious, remove yourself from the vicinity and/or prepare yourself for an encounter. Ready yourself to draw your weapon without displaying it.
2. Draw your weapon. If someone has a gun in your face, you can choose to draw and shoot. Realize that he may shoot first. Also realize that he may have never intended to harm you, or that he may have a toy, or myriad other possibilities. You will be justified in your actions, but you will have to live with the consequences.
3. Let him take your wallet. A robbery alone is not justification for deadly action. A robbery plus a weapon is. If you feel you are not actually in danger, let the wallet go, get on your cell, call the police, and cancel your credit cards.
4. If you truly feel, and you MUST be able to prove this in court, that the perpetrator may take further action after stealing your wallet, you can take the chance and fire. However, if he is retreating at the time, as stated before, it won't hold up in court.
5. Upon seeing the perpetrator retreat, unholster your weapon and keep it pointed down but ready to fire. With your other hand, dial 911 and start explaining the situation, including the fact that you have a weapon. During this phone call one of two things will happen--the thief will leave, and you can reholster and explain the incident to the dispatcher, or the thief will turn to shoot you and hopefully you will have the presence of mind to fire while being seriously distracted from adrenaline and talking on the phone.
6. Run after the jerk and tackle him, punch him in the face and get your wallet back. You might get shot, but you probably won't see any jail time.
None of these options are great. All of them involve risks. Some of them will get you arrested or detained regardless of your innocence or fear for your life.
It doesn't seem right that we can't stop a person who has stolen something vital to us, such as our identity and entire financial life. But in most cases that's how it is. Life can only be taken when life is immediately threatened, not as an afterthought.