[2] Subreption in Catholic Canon law is "a concealment of the pertinent facts in a petition, as for dispensation or favor, that in certain cases nullifies the grant",[3] "the obtainment of a dispensation or gift by concealment of the truth".
[4] When the petition contains a statement about facts or circumstances that are supposititious or at least, modified if they really exist, the resulting rescript is said to be vitiated by obreption, which consists in a positive allegation of what is false.
[4] If, on the other hand, silence had been observed concerning something that essentially changed the state of the case, the concealment or suppression of statements or facts that according to law or usage should be expressed in an application or petition for a rescript is called subreption.
If it is only the impelling cause, and the substance of the petition is not affected, or if the false statement was made through ignorance, the rescript is not vitiated.
It may affect the primary, substantial reason or motive of the grant, or constitute merely a secondary or impellent cause of the concession.