Yeah, I don't get the "God invented horrible unjust laws and instituted them for a time, so now we need to rip the Old Testament out of our Bibles" interpretation of scripture. Almost Gnostic (as in "Wow that Old Testament god was mean and cruel...not like Jesus).
Jesus was not advocating a lawless society. He was enforcing the fact that the Old Testament laws were not for vengeance, but for justice in the carrying out of governmental justice.
So I guess you believe murder is not wrong? You would rather let thousands of people starve and die (innocent, in a worldly sense...children, women, and the underprivileged), spending hundreds of thousands of dollars per inmate, to support these violent criminals for the rest of their life? That is completely insane. God made it clear, before the Mosaic law was even written, that the death penalty was the appropriate punishment for violent.
On a different note, though, the death penalty is only to be carried out on the eye witness testimony of 2 or more witnesses. This should be the standard. The idea that we put to death innocent (in a worldly sense) individuals, is frightening and wrong. There should be no appeal, because only the most rock solid, proven of cases should receive the death penalty in the first place.