Kinjutsu

Kinjutsu (禁術; Literally meaning "Forbidden Techniques") are techniques that have been banned from use, or even from being used. 'Banned' is a loose term, however, for there appears to be no punishments for those that use kinjutsu (other than the ones the technique may cause itself), but those that use it are looked down on. There are many reasons for a kinjutsu to be deemed such, but there are generally three characteristics that can earn a technique the title.
 * The technique violates the laws of nature, as is the case with most Reincarnation Ninjutsu
 * The technique causes so much collateral damage that a single use could wipe out a village and its inhabitants. As such, it is considered too dangerous to be taught to shinobi.
 * The technique causes harm to the user, and in some cases, can lead to their death more easily than normal chakra exhaustion.