Whether Judicial killing is moral or right is another topic entirely. I don't believe that it is either.
Some of you* will be familiar with Karl Popper's Falsification Principle which is a way of demarcating science from non-science. It suggests that for a theory to be considered scientific it must be able to be tested and conceivably proven false. For example, the hypothesis that "all swans are white," can be falsified by observing a black swan.
In moral philosophy we have the Oakeshott Test, which is a means of determining whether an act is likely to be moral, or not. To apply the Test one needs the view of the act from the perspective of Isabel Oakeshott. If one finds oneself to have a more moderate position than Oakeshott, the act can be considered likely to be immoral, if the converse is true and one's position is more extreme than Oakeshott's then the act is logically immoral.
*no, not you, shep.