Q: I just find out that I'm renting an illegal room. The landlord has another tenant, who's subletting the room for me.

A: I'm sorry to hear that you've found yourself in this difficult situation with an illegal sublease. To find relevant case law supporting the idea that the landlord shares responsibility, I would recommend the following steps:

1. Identify the specific laws in your state/locality related to illegal subleases and landlord liability. Landlord-tenant laws vary by jurisdiction. You'll want to search for cases that interpret the statutes most applicable to your situation.

2. Search legal databases like Westlaw, LexisNexis, or Google Scholar using keyword searches that combine terms related to your issue, jurisdiction and the relevant laws. Example searches:

"landlord liability" AND "illegal sublease" AND [your state]

"joint liability" AND "unauthorized sublease" AND "landlord"

3. Focus on cases from your state's highest court or appellate courts, as those will be the most authoritative. Look for cases with facts similar to yours where the court held the landlord liable.

4. Consult a landlord-tenant attorney or local tenants rights organization. They will be most familiar with the controlling case law in your area and can likely point you to the most on-point legal precedents quickly.

5. If you end up in housing court, you can cite the relevant case law you've found to support your argument that the landlord is jointly liable. Hopefully the precedents will help sway the court in your favor.

The most important thing is to find cases interpreting the specific landlord-tenant statutes in your jurisdiction. Caselaw from other states or general common law principles won't be as persuasive. An experienced local attorney is your best resource. I hope you're able to resolve this matter quickly in your favor. Let me know if you have any other questions!