In Ontario, and much of Canada, to call yourself an Engineer you must pass an exam and meet the requirements. Part of this exam is about ethics. In Canada, Engineers have an iron ring to remind them of their duty to society.

The issue is the term "duty" and "public" can get tricky.

How far does duty go? Does it include compromising morals?

Does the "public" include the enemy that we would deploy the technology against?

There is no answer that is without some shortcoming.