Articles 11 and 12 of the Civil Code of the Philippines
Article 11. Customs which are contrary to law, public order and public policy shall not be countenanced. Article 12. A custom must be proved as a fact according to the rule of evidence. Custom is the juridical rule which results from a constant and continued uniform practice by the members of a social community , with respect to a particular state of facts, and observed with a conviction that is juridically obligatory (1 Tolentino, Civil Code, p.38, 1974 ed.). But according to the rules of evidence, a custom must be proven as a fact (Art. 12, New Civil Code). In order that a custom may be considered as a source of right, the following requisites must be proven: 1) plurality of acts; 2) uniformity of acts; 3) general practice by the great mass of the people of the country or community; 4) general conviction that it is the proper rule of conduct; 5) continued practice for a long period of tim...