Conn. Gen. Stat. § 47a § 47a-7b

(a) Upon the request of a tenant, a landlord shall change the locks or permit the tenant to change the locks to a tenant's dwelling unit when: (1) The tenant is named as a protected person in (A) a protective or restraining order issued by a court of this state, including, but not limited to, an order issued pursuant to sections 46b-15, 46b-16a, 46b-38c, 53a-40e and 54-1k that is in effect at the time the tenant makes such request of the landlord, or (B) a foreign order of protection that has been registered in this state pursuant to section 46b-15a that is in effect at the time the tenant makes such request of the landlord; (2) the protective order, restraining order or foreign order of protection requires the respondent or defendant to (A) stay away from the home of the tenant, or (B) stay a minimum distance away from the tenant; and (3) the tenant provides a copy of such protective order, restraining order or foreign order of protection to the landlord. A landlord who is required to change a tenant's locks or permit the tenant to change a tenant's locks under this subsection shall, not later than six hours after receipt of the request, inform the tenant whether the landlord will change the locks or permit the tenant to change the locks. If the landlord agrees to change the locks, the landlord shall do so not later than forty-eight hours after the date that the tenant makes such request.

(b) If a landlord has informed the tenant that the tenant is responsible for changing the locks, fails to change the locks, or fails to permit a tenant to change the locks within the timeframe prescribed under subsection (a) of this section, the tenant may proceed to change the locks. If a tenant changes the locks, the tenant shall ensure that the locks are changed in a workmanlike manner, utilizing locks of similar or improved quality as compared to the original locks. The landlord may replace a lock installed by or at the behest of a tenant if the locks installed were not of similar or improved quality or were not installed properly. If a tenant changes the locks to his or her dwelling unit under this subsection, the tenant shall provide a key to the new locks to the landlord not later than two business days after the date on which the locks were changed, except when good cause prevents the tenant from providing a key to the landlord within the prescribed time period.

(c) When a landlord changes the locks to a dwelling unit under subsection (a) or (b) of this section, the landlord (1) shall, if using a professional contractor or locksmith, be responsible for payment to such contractor or locksmith, (2) shall, at or prior to the time of changing such locks, provide a key to the new locks to the tenant, and (3) may charge a fee to the tenant not exceeding the actual reasonable cost of changing the locks. If the tenant fails to pay the fee, such cost may be recouped by suit against the tenant or as a deduction from the security deposit when the tenant vacates the dwelling unit, but shall not be the basis for a summary process action under chapter 832. For purposes of this subsection, “actual reasonable cost” means the cost of the lock mechanism, as well as the fee paid by the landlord for professional contractor or locksmith services.

(d) A landlord may reprogram a digital or electronic lock with a new entry code to comply with the provisions of this section.

(e) If a tenant residing in the dwelling unit is named as the respondent or defendant in an order described in subsection (a) of this section and under such order is required to stay away from the dwelling unit, the landlord shall not provide a key to such tenant for the new locks. Absent a court order permitting a tenant who is the respondent or defendant in such order to return to the dwelling unit to retrieve his or her possessions and personal effects, the landlord has no duty under the rental agreement or by law to allow such tenant access to the dwelling unit once the landlord has been provided with a court order requiring such tenant to stay away from the dwelling unit, and the landlord shall not permit such tenant to access the dwelling unit. Any tenant excluded from the dwelling unit under this section remains liable under the rental agreement with any other tenant of the dwelling unit for rent or damages to the dwelling unit.

(f) A landlord may not require a tenant who is named as a protected person under an order described in subsection (a) of this section to pay additional rent or an additional deposit or fee because of the exclusion of the tenant who is named as the respondent or defendant in such order.

(g) Any landlord or agent of such landlord who denies a tenant named as a respondent or defendant in an order described in subsection (a) of this section access to the dwelling unit pursuant to this section shall be immune from any civil liability arising from such denial, provided the landlord or agent complies with the provisions of this section and any applicable court order.