If something is right in one situation, it is right in all relevantly similar cases, and if something is wrong in one situation, then it is wrong in all relevantly similar cases.

PROPORTIONALITY

Morally right actions produce more good than harm. An action is wrong if it generates more harm than good, or more evil than good. (NOT to be confused with utilitarianism! This is not a definition of "wrong.") For example, if you do something to avoid harm, you cannot avoid harm by creating more harm than you avoid.

RESPONSIBILITY

Each person is responsible for the foreseeable and intended consequences of her or his action.

ACCIDENTS

No person is responsible for unforeseeable (not "unforeseen"!) consequences, nor for foreseeable harmful consequences against which she or he took reasonable precautions.