Why do celebs get arrested yet paparazzi don't?

Why don't police just arrest the paparazzi??? I mean they har a lot of celebs and can't they be arrested for stalking and harment??? Yet celebs get arrested if they punch them??? I don't blame celebs for attacking them they are after all haring them and what not. So ok they may have aulted them but stalking and haring people is against the law as well so why don't the police arrest the paparazzi as well??? Celebs have a right to be able to go about their lifes without being stalked by paparazzi.