Identify and discuss one argument in opposition to capital punishment. Note that the argument must be based on more than just personal opinion. Cite some information which backs up that argument.

Capital punishment

Identify and discuss one argument in opposition to capital punishment.
You do not need to agree with that position. Also, note that the argument must be based on more than just personal opinion. Cite some information which backs up that argument. (Do this whether you agree with that particular position or not.)

Obviously, social science data is best.