Star Wars: How EVERY Jedi Got On The High Council

Anakin Skywalker's inclusion to the Council was a crafty move put in place by the Council themselves. Following Anakin's defeat of Count Dooku and the rescue of Chancellor Palpatine, the Jedi began to sense great darkness surrounding Palpatine, and used Anakin's relationship with the leader to spy on him.

Placing him on the Council without giving him the rank of Master, they hoped to gain intelligence about the Chancellor's activities.

The whole plan would ultimately backfire, pushing Anakin further to the Dark Side and deepening his distrust of the Council, all as Palpatine had planned.