An assassin is defined as, “Someone who murders an important person," and assassination as, “The act of murdering an important person" (LDOCE online). Just as looking only at both definitions, it is found that there is the "murder" word in the both. If people use only definition as an element to determine whether the assassination is justify or not, they might not have strong evidence to prove that the assassination is totally unacceptable. Because the assassination is an act, it is, hence, useful to use ethics, the concept of goodness, to consider this issue: consequentialism, and utilitarianism.
A principle of ethical issue that would be discussed firstly is consequentialism determining a good act from its final result. Some individuals, especially who agree with the assassination, strongly believe that some of important person doing a lot of worst effects to their social should not live in their position so that these bad-doing person will not absolutely have authority to do so. Since there is no good solution, it seems that assassination is the last choice to get rid of the bad. However, it is uncertain if the assassination will turn the results out as what have been hoped, i.e. the bad events may not disappear. For example, killing a head of protestors does not mean that it can ged rid of a protest or prohibit it. Because of an ultimate uncertain effect of assassination comparing to murdering itself, the assassination should not be justified.
A second ethic, which should be applied to judge about the assassination, is utilitarianism. To act in a way that is useful or greatly happy for the greatest number of people is a basis of utilitarianism. The most of assassination in the past usually occur to the very important politicians. Though it was argued that the assassination bring to the big change in society, mostly in the better ways, the most of murdering action, such as assassination of JK Kennedy, or Luther King, aimed secretly for the benefits of only few person. Therefore, it is hard to agree with anyone supporting the assassination because of its great merit for lots of citizen.
Assassination is an act that should not be justified. Using two approaches, definition and ethics, are enough to determine that assassination or murdering someone is totally unacceptable in any society.