To what extent do the ends justify the means?
Fairly straight forward question, I think. I encourage you to ask for clarification though. One possible "end" that you could talk about the means for is science (touched on in the Milgram experiment). How far should our experiments go before we can justify the knowledge of the results? You can definitely use your own examples; that was just a possible route.
Means: torturing someone; Ends: information for national security