I am going to assume you're asking about an unlawful detainer action--you don't say what kind of case it is.
The certified notice is evidence of the breach of warranty of habitability. Moreover, if the landlord hasn't complied with the notice within 35 days of the violation, the landlord cannot bring a lawsuit for unlawful detainer under Civil Code section 1942.4. That would be the strongest defense, because if the landlord is in violation he can't accept rent legally.
The breach of the covenant of quiet enjoyment is not a strong defense in unlawful detainer, so I would skip that one.
Not necessarily. It is good evidence for uninhabitability (not breach of quiet enjoyment), but it still might not be conclusive evidence of what you intend to prove.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, consult with your own attorney.
While I cannot give you legal advice in this forum, did you inform the landlord? If not, that is generally your first step. As a general matter, you have to givel the landlord a reasonable opportunity to fix the problem before you can begin making these types of arguments.
THIS RESPONSE IS INTENDED TO CONVEY GENERAL INFORMATION ONLY. IT SHOULD NOT BE RELIED UPON OR TAKEN AS LEGAL ADVICE. FURTHER, THIS RESPONSE IS NOT INTENDED TO AND DOES NOT CREATE AN ATTORNEY-CLIENT RELATIONSHIP.