Kinjei (Earth-2356)

Kinjei are Force techniques that have been banned from being taught or used by the Jedi in an agreement between the Jedi Order and the Galactic Republic previewed in the Galactic Constitution. Because of their corrupting and adictive nature with the dark side of the Force, they were sought by rogue Jedi and the Sith.

These bans were put in place by the Jedi High Cocunil for any number of reasons, but forbidden Techniques can generally be put in one of three categories:

Techniques that cause harm to the user themselves, such as the Wind Release: Wind Saber, which the mere use of is both highly useful as well as detrimental to the user. Although, with training, a user can overcome this weakness by compensating for it, enabling them to use the technique without any consequences, such as Luke Skywalker's throwing of the Wind Saber to avoid damaging himself. However, there are some that cannot avoid self-harm/sacrifice, such as Dead Demon Consuming Seal or Creation Rebirth.

Techniques that violate the laws of nature and ethics/morality (e.g. Outer Path — Samsara of Heavenly Life Technique, and the Summoning: Impure World Reincarnation, which reincarnates the dead with a sacrifice).

Certain techniques that are known to cause massive collateral damage, such as the total destruction of a city and end with the death of everyone in it, thus the great moral ramifications of its potential lead many to labelling it as a forbidden technique (e.g. the Fury technique).

Despite being banned, the mere use of these techniques generally did not carry any legal consequences for members of the Jedi Order during the days of the Galactic Republic, except those brought on by the techniques themselves. However, their use was heavily frowned upon, especially those techniques that violate nature and ethics, mostly which were used by the Sith Order before its downfall and rogue Jedi.

On the other hand, researching on and creating forbidden techniques was punishable, as Orochimaru was banished from Coruscant's Jedi Order after being caught using live people as guinea pigs, while Deidara was forced to leave Iwa's Jedi Order when he stole a forbbiden technique to develop his passion for art.

Source

 * https://naruto.fandom.com/wiki/Kinjutsu.