Quiet Enjoyment and Breaking the Lease

My question involves landlord-tenant law in the State of: Arizona

I have signed a lease with four other room mates, each of our names are on the contract. Since day one they were doing things that were prohibited in the contract. They would not stop until I talked to the landlord who talked to them and gave them a warning. Since then, they still do those things secretly. Also, one of their girlfriends is always over and almost always sleeps over. The roommates and one of their girlfriends are always loud until 1-2am at night. I can't fall asleep until they're asleep. It got to the point where I had to sleep in the car one night. What can I do to break the lease and leave? The contract states if one roommate leaves, the other ones still have to pay the total monthly rent.

Your poor choice of roommates is not the fault of your landlord, nor is it your landlord's duty to make your roommates stop "doing things" that annoy you. Nothing you have written will excuse you from your obligation to your landlord under the lease.

What if I reported them for continuing to smoke even after they were given a warning?

The landlord could evict ALL of you. That's probably not what you want.

You can leave. And the roommates can sue you for your share of the rent, and they will win in court. Having done the "dealing with crappy college roommates" thing, I can tell you that your only real, feasible option is to leave at the conclusion of your lease term.