Thanks for using Avvo. Please note that I am not licensed to practice law in the state of California. Due to the high volume of questions right now, it may take longer for some of our loyal Avvo lawyers to get back to you. In the meantime, I wanted to offer some preliminary help.
There are many kinds of defects that could make a rental unit unlivable. A rental unit may be considered unlivable if a nuisance endangers the health, life, safety, property, or welfare of the occupants, but keep in mind that California laws does not hold landlord's responsible for damages caused by the tenant, tenant's guests, or pets. I have attached is a web link to access information on landlord tenant law and other housing issues.
You should consult a top Avvo-rated lawyer in your area. Good luck.
I am licensed in California. Please note that only licensed attorneys can give you legal advise in the state of California. For an unlicensed person to give legal advice in California is a crime, and I believe that applies equally to website postings.
First of all, I see that you are in Los Angeles. You should call the Los Angeles Housing Department (866) 557-RENT and ask for a Code Enforcement Inspection. You should do the same with the Los Angeles County Environmental Health Department (626) 430-5200. These agencies can both order your landlord to exterminate the bedbugs. If your landlord refuses, he could end up with a criminal complaint against him. Please do this as soon as possible because this is the fastest way to fix the problem.
Your girlfriend does have a case for personal injury. Please note that she has only two years to file a lawsuit. In the off-chance you live in a building owned by the government, she may have to make a claim within six months, so please consult a (licensed) attorney promptly to make sure all your rights are protected.