Of the Formation of the Laws.
ART. 51. The formation of all laws and decrees may begin indistinctly in either of the chambers, except those having for their object the levying of contributions or of raising taxes, which must originate in the Chamber of Deputies.
1st. Propositions which the President of the United Mexican States shall deem advantageous to the Union and which as such he shall specially recommend to the Chamber of Deputies.
2d. Propositions, projects of laws or decrees, which the legislatures of the states may address to either chamber.
ART. 53. All projects of laws or decrees without any exception whatever shall be successively discussed in the two chambers, observing in both with exactness what it prescribed in the regulations as to the form of debate, as well as to the delays and modes of proceeding in voting.
ART. 54. Propositions of laws or decrees, which have been rejected in the chamber, where they originated, before the final reading cannot again be proposed by any member during the sessions of that year, nor until the ordinary sessions of the years following.
ART. 55. If the propositions of laws or decrees after having been discussed be approved by an absolute majority of the members present in both chambers, they shall be sent to the president of the United States, who if he also approves shall sign and publish the same; and if not, shall return them with his observations within ten working days to the chamber whence they originated.
ART. 56. The propositions of laws or decrees returned by the president, according to the preceding article, shall be a second time discussed in the two chambers. If in each of them, they be approved by two-thirds of the members present, they shall again be sent to the president, who without further excuse must sign and publish them; but if not approved by the votes of two-thirds of the members, they cannot again be proposed until the year following.
ART. 57. If the president should not return a proposed law or decree within the period prescribed in the 55th article, it shall be considered as approved by that very fact, and be promulgated as law; unless while the delay is not yet expired, congress should have closed or suspended its sessions, in which event the return must be made on the first day thereafter when congress shall again unite.
ART. 58. The projects of law or decrees once wholly rejected by the chamber of revision, shall be returned by said chamber to that in which it originated. If upon re-examination in the latter, it be approved by two-thirds of the members present, it shall be sent back again to the chamber by which it was rejected, who shall not again reject it, unless by the vote of two-thirds of the members present.
ART. 59. All proposed laws or decrees, which, on a second examination, have been approved by two-thirds of the members of the chamber where they originated, and not disapproved by two-thirds of the chamber of revision, shall be sent to the president who must sign and circulate them, or send them back within ten working days to the chamber where they originated.
ART. 60. All propositions of laws or decrees which, according to the preceding article, the president may send back to the chamber where they originated, shall be again considered, and if they are approved by two-thirds of the members present, and the chamber of revision be not equally divided, they shall be returned to the president, who shall cause them to be published. But if in their origin they were approved by two-thirds of the chamber, or disapproved by an equal number of the chamber of revision, they cannot again be taken up except at a subsequent regular session.
ART. 61. In case they should be reproved a second time by the chamber of revision, according to article 58, the proposition shall be considered as thrown out, and it cannot again be taken up until the following year.
ART. 63. The portions of a proposed law or decree, which may be once disapproved by the chamber of revision, are subject to the same formalities as those propositions which have been wholly disapproved.