Yeah, if they don't let you, you can sue the district. However, what you should ask yourself is: Would it be smart for you to play football?
It seems you love the game; that's great. However, there are risks involved in football in terms of your future. The main ones would be concussions and physical injuries. Are you a track star? Because it's almost impossible for you to get a football scholarship for college, and if you get injured, good-bye track scholarship. If you have really good grades, the time and potential concussions from football could affect your grades, and therefore your ability to go to a good college. Also, consider how it could affect your social life. If you think the pros outweigh the cons, go ahead. If not... well, you get the idea.