How can I prepare for a Landlord/Tenant hearing against freeloading brother?

Here's the deal: My father owns a duplex home. He lives downstairs with my sister and 10 month old niece. I live upstairs with my brother. My 30 year old brother came home after 4 years in jail for armed robbery and drug possession in Dec. 2006. It took him 5 months to get a job, whereupon my father told him he was to pay half of the total bills - he agreed. He then began using drugs again and was not paying any bills. We confronted him numerous times and gave him plenty of chances to get his act together. Eventually, he lost his job and started growing and selling pot from the house. I have called the police on a few occasions but they haven't found anything or caught him in the act. He has punched holes in walls out of anger, and even pushed my sister down when she was 6 months pregnant when she confronted him over not paying a $40 phone bill. She wouldn't press charges or call the police and she refused to get involved in the eviction process. My father filed a landlord tenant complaint under a "month to month" verbal lease. my brother claims he will be fighting the eviction and will have my sister testify that there was no verbal lease, which is completely untrue. My question is, how do I best prepare for this hearing, and is there a chance he won't be evicted? I live in Pennsylvania.