When should a tech company refuse to build tools for the government?

During the second world war, IBM supplied the Nazis with technology used to help transport millions of people to their deaths in the concentration camps. The American technology company leased punch-card machines through a German subsidiary for the purpose of tabulating a population census, which allowed the Nazis to identify and track the movements of Jews all the way to the gas chambers. So helpful were IBM's machines that Hitler awarded a special medal to the company's CEO, Thomas Watson, in recognition of his services to the Third Reich. This shameful episode in IBM's history highlights an uncomfortable predicament for companies pursuing lucrative government contracts, and one that's recently reared its head for Google, Microsoft and Amazon: should they be held accountable for how their customers deploy their technologies? The question has come to the fore for Microsoft, after it was revealed that the company's Azure cloud computing arm was working with US Immigration and Customs Enforcement (Ice).