This paper, beside to make a recount of the "similar states" as generator cause of insanity in the current criminal code, tends to explain how these states are understood by the doctrine: (i) those who see that they are unconstitutional because they involve a constitutionally prohibited analogy in criminal matters and (ii) those who do not observe any constitutional objection. Within the latter group there are two positions, on the one hand, those who believe they have fully implemented and on the other hand, those who see any similar state can be suitable either mental disorder or psychological immaturity. It concludes by mentioning the new way of understanding the causes of insanity through "Similar states".