New tenant with no consent given

I am currently renting a room in a house with two other individuals. The house is located in Phoenix, AZ. We were contacted today by the landlord, who lives in CA, to inform us that a new roommate was moving in tomorrow. None of us have met this person, nor has the landlord. Is this legal? If not, what actions can/should be taken to prevent this? He has done this before and we have had serious problems with the people moving in, including drug, mental health, and other issues.

[annjd]

What does your lease say? Do you have just the room and did you know that others would be renting?

By the way some local jurisdictions do not allow that kind of renting by the room without certain permissions; you may if you wish check with city officials as well.

The lease doesnt say anything about the situation. We all rent one room but there is a large common area which is shared by all of us.

Your agreement hasn't changed then. You still only rent ONE room and will continue to share the common area. So how is this any different than renting in an apartment complex where each person has their own quarters, but share the common halls, lawn, and laundry areas? You only rent a room; you have no say in who rents the other rooms. If you want a voice in who lives near you, you and your roommates need to lease the entire house with an approval for subleasing. You could then pick your own roommates to live in your rented unit. Why not approach the landlord with this solution? Of course, this would make you responsible for the entire rent instead of a small portion of it. But with the greater responsibility and obligation comes the right to choose.