No, deterrent as a concept is completely proven.
Anyone stating deterrent doesn't work are talking unprovable nonsense. icon_wink.gif
Yes it's a deterrent.
The question though is how effective it is, "not very" would be my answer to that.
Then you have to look at the cost, innocent people being killed because there will always be mistakes in the system, hmmm no thanks.
As to the monetary cost, whatever, justice shouldn't be dealt on a cost bases, that's something you do when shopping, not deciding on a suitable legal system.