There is a interesting (but expensive) book about this topic , from the blurb:
Movements to abolish the death penalty cannot be understood without a grasp of the dynamics of public opinion on capital punishment, which is driven not by rational consideration but by what cognitive psychologists call 'social intuitions,' deeply rooted attitudes which are resistant to change. European death-penalty abolitionists quickly realized the futility of trying to change public opinion on a mass scale, and instead devised strategies to accomplish abolition despite lingering public support for the death penalty. Pointing to the importance of political structures that allowed European abolitionists to bypass public opinion, this study assesses the prospects of the 'European model' of abolition in global perspective.
Get dozens of book recommendations delivered straight to your inbox every Thursday.