What did the court decide in Green v. Superior Court?
Answered for: California
we have determined that the Hinson court properly recognized a common law implied warranty of habitability in residential leases in California, and we conclude that the breach of such warranty may be raised as a defense in an unlawful detainer action
California's Supreme Court adopted the implied warranty of habitability and allowed it as a defense in an eviction case.
This answer is true in California and nowhere else on this site. Another jurisdiction is another answer, or an honest gap: see what has been read for California.