Article 131 Political Constitution of the United Mexican States

It is the exclusive power of the Federation to tax goods that are imported or exported, or that pass in transit through the national territory, as well as to regulate at all times and even prohibit, for reasons of security or police, the circulation in the interior of the Republic of all kinds of effects, whatever their origin.

The Executive may be empowered by the Congress of the Union to increase, decrease or suppress the rates of the export and import tariffs, issued by that same Congress, and to create others; as well as to restrict and to prohibit imports, exports and the transit of products, articles and effects, when it deems it urgent, in order to regulate foreign trade, the economy of the country, the stability of national production, or to carry out any other purpose, the benefit of the country. The Executive itself, when sending to the Congress the Fiscal Budget of each year, shall submit to its approval the use it has made of the power granted.