Canon 127. §1 When the law prescribes that, in order to perform a juridical act, a Superior requires the consent or the advice of some college or group of persons, the college or group must be convened in accordance with can. 166, unless, if there is question of seeking advice only, particular or proper law provides otherwise. For the validity of the act, it is required that the consent be obtained of an absolute majority of those present, or that the advice of all be sought.
[NB see Authentic Interpretation of canon 127 §1, 5.VII.1985]

§2 When the law prescribes that, in order to perform a juridical act, a Superior requires the consent or advice of certain persons as individuals:

1° if consent is required, the Superior’s act is invalid if the Superior does not seek the consent of those persons, or acts against the vote of all or of any of them;

2° if advice is required, the Superior’s act is invalid if the Superior does not hear those persons. The Superior is not in any way bound to accept their vote, even if it is unanimous; nevertheless, without what is, in his or her judgement, an overriding reason, the Superior is not to act against their vote, especially if it is a unanimous one.

§3 All whose consent or advice is required are obliged to give their opinions sincerely. If the seriousness of the matter requires it, they are obliged carefully to maintain secrecy, and the Superior can insist on this obligation.