>>149394563The GLs are supposed to operate within the limits of their home planet's laws. So they can only "enforce law" as far as the people in the planet are willing to accept. One of the reasons why Sinestro was expelled from the GL corps was because he used the GL powers to impose his own standards and control the government. The guardians assume the GLs will need to skirt the rules here and there, but they don't want to straight up be against local governments because that would just eventually snowball into planets making alliances and armiest against them.
The guardians have their own authority based on being some of the oldest beings in the universe too but even that is open for discussions. The JL cartoons actually talks about how fragile this unspoken agreement is because GLs are expected to also hand themselves over to any authority tied to the jurisdicitions they oversee or act in. So when Jon Stewart is accused of destroying a nearby planet, he's also expected to hand himself over and get any punishment the local lawgivers give to him, so the other GLs can keep working around the galaxy without bigger issues.
Yet another reason why GLs are chosen from the native planet's population rather then them just picking the best of the universe and assigning them in a more invasive way. They have have training programs, most GLs were already accomplished in their own way in their non-GL life, with Hal being a pilot, Kilowagg being an engineer, etc.