Canon 124. §1 For the validity of a juridical act, it is required that it be performed by a person who is legally capable, and it must contain those elements which constitute the essence of the act, as well as the formalities and requirements which the law prescribes for the validity of the act.

§2 A juridical act which, as far as its external elements are concerned, is properly performed, is presumed to be valid.

§1. Ad validitatem actus iuridici requiritur ut a persona habili sit positus, atque in eodem adsint quae actum ipsum essentialiter constituunt, necnon sollemnia et requisita iure ad validitatem actus imposita.

§2. Actus iuridicus quoad sua elementa externa rite positus praesumitur validus.

Canon 125. §1 An act is invalid if performed as a result of force imposed from outside on a person who was quite unable to resist it.

§2 An act performed as a result of fear which is grave and unjustly inflicted, or as a result of deceit, is valid, unless the law provides otherwise. However, it can be rescinded by a court judgement, either at the instance of the injured party or that party’s successors in law, or ex officio.

§1. Actus positus ex vi ab extrinseco personae illata, cui ipsa nequaquam resistere potuit, pro infecto habetur.

§2. Actus positus ex metu gravi, iniuste incusso, aut ex dolo, valet, nisi aliud iure caveatur; sed potest per sententiam iudicis rescindi, sive ad instantiam partis laesae eiusve in iure successorum sive ex officio.

Canon 126. An act is invalid when performed as a result of ignorance or of error which concerns the substance of the act, or which amounts to a condition sine qua non; otherwise it is valid, unless the law provides differently. But an act done as a result of ignorance or error can give rise to a rescinding action in accordance with the law.

Actus positus ex ignorantia aut ex errore, qui versetur circa id quod eius substantiam constituit, aut qui recidit in condicionem sine qua non, irritus est; secus valet, nisi aliud iure caveatur, sed actus ex ignorantia aut ex errore initus locum dare potest actioni rescissoriae ad normam iuris.

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.

§1. Cum iure statuatur ad actus ponendos Superiorem indigere consensu aut consilio alicuius collegii vel personarum coetus, convocari debet collegium vel coetus ad normam can. 166, nisi, cum agatur de consilio tantum exquirendo, aliter iure particulari aut proprio cautum sit; ut autem actus valeant requiritur ut obtineatur consensus partis absolute maioris eorum qui sunt praesentes aut omnium exquiratur consilium.

§2. Cum iure statuatur ad actus ponendos Superiorem indigere consensu aut consilio aliquarum personarum, uti singularum:

1° si consensus exigatur, invalidus est actus Superioris consensum earum personarum non exquirentis aut contra earum vel alicuius votum agentis;

2° si consilium exigatur, invalidus est actus Superioris easdem personas non audientis; Superior, licet nulla obligatione teneatur accedendi ad earundem votum, etsi concors, tamen sine praevalenti ratione, suo iudicio aestimanda, ab earundem voto, praesertim concordi, ne discedat.

§3. Omnes quorum consensus aut consilium requiritur, obligatione tenentur sententiam suam sincere proferendi atque, si negotiorum gravitas id postulate, secretum sedulo servandi; quae quidem obligatio a Superiore urgeri potest.

Canon 128. Whoever unlawfully causes harm to another by a juridical act, or indeed by any other act which is deceitful or culpable, is obliged to repair the damage done.

Quicumque illegitime actu iuridico, immo quovis alio actu dolo vel culpa posito, alteri damnum infert, obligatione tenetur damnum illatum reparandi.