First, Do No Harm - A Hippocratic Oath for Coders?

rhysweatherley asks: "With the increase in spyware, spam, etc, is it time for a Hippocratic Oath for Programmers? Should programmers be able to refuse to write code that harms the public more than it helps? Should they code defensively to prevent software and information being misused for unintended purposes? And how do we protect such programmers from being dismissed unfairly for standing on principle?"