[@Star Lord]

Feel free to interpret the Nova Corps however you need for your story.

So far as the GLC... they're basically Interpol. I can't see them having a standing agreement with the Ravagers.  I could see one or more Green Lanterns maintaining confidential informants inside a group like a Ravagers, but piracy and the mafia are the main things that my Green Lantern story is focused on from a law enforcement angle.