I'm with Spats on this one.
The threat of harm or the threat of punishment do not seem to be really effective deterrents.
We all hear how released criminals, ostensibly rehabilitated members of society, often go on to re-offend. Clearly, the thought of prison either isn't scary, or isn't even considered.
There is evidence showing that the existence of the death penalty does not result in a reduction of murders. Indeed, such states often have higher murder rates than the states without such a punishment.
So, in the case of CCW, I feel it may tip the scales more in the favour of the intended victim (as, no doubt, they'd been chosen because the criminal felt they either yielded good pickings, easy pickings or both).
Therefore, all I would be willing to say is that if victim of crime turns out to be carrying, it may give the criminal cause to regret committing the crime, but by then the offence has already been set in motion and so technically has occurred, regardless of the outcome...
You cannot wake someone who is pretending to sleep. Stop pretending. Wake up.
Freedom: Please enjoy responsibly.
Any idea that relies on murder for its survival in intrinsically weak.