From Halopedia, the Halo wiki
2535 was a year in the 2530s in the 26th century. It was a turning point in the Human-Covenant War. With the destruction of Jericho VII, most major Outer Colonies had been destroyed. In order to protect Earth and the remaining colonies, the Cole Protocol was established by military order. Human ships must, when forced to withdraw, not move on to a colony-bound vector, even if that means jumping without proper navigational calculations. If blind jumps are not possible, the ship's commanding officer must order a self-destruction sequence if capture is imminent. In addition, it is also imperative that the shipboard AI construct's data core not fall into Covenant hands; thus, part of this protocol involves either the removal or destruction of the ship's AI in extreme situations. Additionally, no captured Covenant ships or technology may be brought back to a human planet without being checked extensively for surveillance devices.