What is Situation Ethics?
In situation ethics, right and wrong depend upon the situation.
There are no universal moral rules or rights - each case is unique and deserves a unique solution.
Situation ethics rejects 'prefabricated decisions and prescriptive rules'. It teaches that ethical decisions should follow flexible guidelines rather than absolute rules, and be taken on a case by case basis.
So a person who practices situation ethics approaches ethical problems with some general moral principles rather than a rigorous set of ethical laws and is prepared to give up even those principles if doing so will lead to a greater good.
Since 'circumstances alter cases', situationism holds that in practice what in some times and places we call right is in other times and places wrong...
For example, lying is ordinarily not in the best interest of interpersonal communication and social integrity, but is justifiable nevertheless in certain situations.
Joseph Fletcher, Naturalism, situation ethics and value theory, in Ethics at the Crossroads, 1995
Situation ethics was originally devised in a Christian context, but it can easily be applied in a non-religious way.