“Moreover, ‘legitimate defence can be not only a right but a grave duty for someone responsible for another’s life, the common good of the family or of the State’ (CCC 2265). Unfortunately it happens that the need to render the aggressor incapable of causing harm sometimes involves taking his life. In this case, the fatal outcome is attributable to the aggressor whose action brought it about, even though he may not be morally responsible because of a lack of the use of reason.” (Pope Saint John Paul II; Evangelium Vitae #55; March 25, 1995)