A sentence suffers from the defect of remediable nullity only if: 1/ it was rendered by an illegitimate number of judges contrary to the prescript of can. 1425, §1; 2/ it does not contain the motives or reasons for the decision; 3/ it lacks the signatures prescribed by law; 4/ it does not indicate the year, month, day, and place in which it was rendered; 5/ it is based on a null judicial act whose nullity was not sanated according to the norm of can. 1619; 6/ it was rendered against a party legitimately absent according to can. 1593, §2.
Source: Code of Canon Law (Vatican.va)