I'd say that it never makes sense for any crime, Julian, unless you define "sense" as satisfying a primitive lust for revenge and satisfaction that someone has apparently got his just come-uppance. It is a primitive relic of the past and it should be forgotten forthwith. As Michael correctly says, it is not and has never been a deterrent against any sort of crime - people who commit major crimes rarely think that far ahead and in any case, the natural human "but it'll never happen to me" feeling kicks in. Moreover, it is applicable against so few criminals that the economic benefits of murdering them v. keeping them inside for life are non-existent. It serves absolutely no purpose in a civilised society.