Conn. Gen. Stat. § 52-175: Entries and memoranda of mentally ill and incapable persons.

(a) In the trial of any civil action in which any party is, at the time of the trial, mentally ill or unable to testify by reason of incurable sickness, failing mind, old age, infirmity or senility, the entries and memoranda of the party, made while he was sane and which are relevant to the matter in issue, may be received as evidence.

(b) If the entries and memoranda of any such mentally ill person or person unable to testify would be admissible, under the provisions of this section, in his favor in any action to which he is a party, the entries and memoranda may be admitted in favor of any person claiming title under or from the mentally ill person or person unable to testify.

(c) The court shall determine, upon competent evidence, as a preliminary question of fact, whether the provisions of this section apply to any party or parties to any action on trial before it.