In the year of my birth, which now seems to me a very long time ago, C. S. Lewis wrote a short and incisive essay entitled The Humanitarian Theory of Punishment (link is no longer available). In this essay, Lewis drew attention to the potential for tyranny of this seemingly humane theory, according to which people were to be treated not according to their deserts, but according to what would make them ‘better’ on whatever scale of goodness was adopted by the therapists, who of course would also decide whether or not the wrongdoers were ‘cured.’
The horrors that Lewis foresaw as following from the humanitarian theory of punishment were those of cruelty and oppression disguised as benevolence.