>Be careful with this argument. Cops also don't have any "obligation" to stop crime, so if we take this argument to its logical conclusion, then it's fine (or at least, it's "not unilaterally overriding laws") for a cop to stand by while someone gets lynched.
You're just figuring that out now? You're 50 years late[0] for Warren v. District of Columbia (rape, assault and burglary) and 20 years late[1] for Castle Rock v. Gonzales (triple murder).