If she’s not on the lease, can’t you (the folks actually on the lease) be subject to eviction for violating your lease?
What a cruddy situation.
Unfortunately also true…in my case I am the property owner and I am free to take on boarders as I see fit. The situation changes if I were to rent out the whole house to a third party, mainly with my homeowners insurance.
Here’s some passive aggresive and active-aggressive techniques for encouraging a roomate to leave. Some of these are quite effective (try to guess which ones…I think you’ll be pleasently surprised).
http://boards.straightdope.com/sdmb/showthread.php?postid=2638708#post2638708
Regarding the advice to change the locks and throw her stuff on the lawn:
A friend of mine owns a house and had a tenant move in. They only had a verbal agreement, but the tenant lied about his previous housing situations and it turned out he had a felony conviction. My friend flipped out and asked the guy to move out. When he didn’t move out, he threw all the guy’s stuff out of the house and changed the locks. When my friend came home from work the next day, he found that the locks had been changed again, and the tenant’s stuff was back in the house. My friend had to call a locksmith to let him in to his own house and get a new key made. It turned out the tenant was completely within his legal rights, since my friend had not followed the proper legal procedure for eviction. No matter that the agreement was verbal. His rash actions caused a bad situation to become much worse, and a serious lesson in landlord/tenant issues was learned the hard way.