Conn. Gen. Stat. § 47a-33: (Formerly Sec. 52-540a). Defense that action is retaliatory.

In any action for summary process under this chapter or section 21-80 it shall be an affirmative defense that the plaintiff brought such action solely because the defendant attempted to remedy, by lawful means, including contacting officials of the state or of any town, city, borough or public agency or filing a complaint with a fair rent commission, any condition constituting a violation of any of the provisions of chapter 368o, or of chapter 412, or of any other state statute or regulation or of the housing or health ordinances of the municipality wherein the premises which are the subject of the complaint lie. The obligation on the part of the defendant to pay rent or the reasonable value of the use and occupancy of the premises which are the subject of any such action shall not be abrogated or diminished by any provision of this section.