Art. 5. Acts executed against the provisions of mandatory or prohibitory
laws shall be void, except when the law itself authorizes their validity.
A mandatory law is one which prescribes some element as a requirement (i.e., wills
must be written – Article 804; form of donations – Article 749)
A prohibitory law is one which forbids something (i.e., joint wills – Article 818)
General Rule: Acts which are contrary to mandatory or prohibited laws are void.
1. When the law itself authorized its validity (i.e., lotto, sweepstakes)
2. When the law makes the act only voidable and not void (i.e., if consent is vitiated,
the contract is voidable and not void)
3. When the law makes the act valid but punishes the violator (i.e., if the marriage is
celebrated by someone without legal authority but the parties are in good faith,
the marriage is valid but the person who married the parties is liable)
4. When the law makes the act void but recognizes legal effects flowing therefrom
(i.e., Articles 1412 & 1413)