Unless you have prior knowledge of my proclivity to violence, or some other factor, my sharing proximity to you does not give you the legal option to employ violence, EVER.

The problem with the sort of change you are sort-of proposing is that if following someone triggers self-defense exemption to assault you have just turned the sidewalk of every major city and shopping mall into a free-fire zone. God help anyone who goes to Disney World and waits in line for Its a Small World.

I agree with you that the law was not applied fairly. If it had (based on the evidence) Zimmerman would never had been charged. Research other cases. I suggest you save your outrage in case Michale Dunn is not convicted for he surely deserves it much more than Zimmerman, though I doubt you even know who he is.