That verse has to do with a personal type of insult (slapping somebody on the right cheek, much like today spitting at somebody or giving him the finger) used in that culture, not a crime requiring a personal defense.
Kudos.
And for those who would continue to dissemble on this issue and need an illustration of how things might work out in an interface between these two things, reference what happened in Georgia this weekend with Ashley Smith and Brian Nichols.
Note that Ashley DID go ahead and call in Nichols' location when it was reasonable to do so. And she is non-committal when asked about whether he should or should not receive the death penalty.
I personally did NOT agree with Pat Robertson's support of commuting the death sentence of the Christian female convict in Texas just because she converted and became a productive member of society (in prison) after killing two people with an axe (under drug influence?) Just because someone repents and changes their behavior does NOT excuse two murders, and I suspect Ashley Smith is similarly minded. And I'll bet she believes in defending yourself to the GBI (great bodily injury) level if opportunity presents itself and if there are no other reasonable options.
At this point in time, from my OWN Bible study, I am persuaded that the Noahic Covenant, so called, included the death penalty for murder for the very reason that the Great Flood became necessary: increasing lawlessness and violence. We are seeing similar effects nowadays when "three strikes, you're out" laws are passed.