If there's one thing that's completely bizarre about the DC universe, it's the way the Green Lanterns are used. While they were initially intended as the noble can-do-no-wrong police of the galaxy, various comic runs and storylines have had them appear more like supervillains than anything else.
And when they're not terrorising the galaxy they've sworn to protect, the Green Lanterns are making the lives of their own members miserable, via a mixture of not properly training them, and not policing their own members when they do awful, awful things - unless it makes them look good to other people, of course.
Sure, being the peacekeepers for an entire galaxy is by no means an easy job. In fact, it's one that almost dictates that you do some pretty sketchy stuff along the way for the greater good. But the structure of the Green Lanterns themselves seems tailor-built to ensure that their members are forced into pretty nasty situations without any help from the people they are supposed to consider their team.
Tragically, there's no Federal Bureau of Investigation for the DC universe, because they'd quickly find that the life-ruining policies of the Green Lantern Corps often make them no better than the people they are fighting and killing much of the time.