Obama Administration Says Shell Cannot Drill in the Arctic

Because they "screwed up" in the past

Shell "screwed up" drilling for oil in Arctic waters and will not be allowed back without a comprehensive overhaul of its plans, the Obama administration said on Thursday. 

A government review found the oil company was not prepared for the extreme conditions in the Arctic, which resulted in a series of blunders and accidents culminating in the New Year's Eve grounding of its drill rig.