Yeah, but they don't just limit the crimes they patrol and arrest for to genocide, it can be any kind of crime like smuggling, trafficking, etc.
There are actual intergalactic laws they cite when they arrest someone.
And protocols too, i remember when in Final Crisis they had a term for death gods and all.
"Wow. You made Spider-Man sad, congratulations. I stabbed The Hulk last week"
Wolverine, Venom Annual # 1 (2018)
Nobody does it better by Jeff Loveness