…a [Nazi] Ministry of Justice Commission on the Reform of the Criminal Code drafted a similar law sanctioning “mercy killing” of people suffering from incurable diseases. The law read, in part: 

“Clause 1 Whoever is suffering from an incurable or terminal illness which is a major burden to him or others, can request mercy killing by a doctor, provided it is his express wish and has the approval of a specially empowered doctor. 

“Clause 2 The life of a person who because of incurable mental illness requires permanent institutionalisation and is not able to sustain an independent existence, may be prematurely terminated by medical procedures in a painless and covert manner.” 

From Forgotten Crimes by Susanne E Evans

Notice that the first clause is almost exactly what those seeking to advance euthanasia in the UK are putting forward as a reasonable legal measure. And notice the easy and natural step to by-passing the question of voluntary choice for those who might be deemed lacking mental capacity.

There is hardly a break between euthanasia and eugenics – the first creates the licence to ignore the dignity of human life, the second gives others the duty to ignore it.