The Maquila Decree, established in 1989, lays out the legal requirements for foreign operations in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. As described by the Bancomext Mexican Showroom, an organization to promote foreign investment in Mexico, this program allows foreign companies to build and operate factories

Factory

A factory or manufacturing plant is an industrial building where laborers manufacture goods or supervise machines processing one product into another. Most modern factories have large warehouses or warehouse-like facilities that contain heavy equipment used for assembly line production...

 in virtually any Mexican location of their choosing. These companies are allowed to import materials and equipment duty-free, the only limitation being that these items will at some unspecified date be removed from Mexico. For these reasons, items manufactured in Mexico are generally export

Export

The term export is derived from the conceptual meaning as to ship the goods and services out of the port of a country. The seller of such goods and services is referred to as an "exporter" who is based in the country of export whereas the overseas based buyer is referred to as an "importer"...

ed.

As for the items being manufactured, there are virtually no restrictions other than obtaining a special permit if the product involves radioactive material or firearm

Firearm

A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

s. The limitations are so lax that even activities such as data processing

Data processing

Computer data processing is any process that a computer program does to enter data and summarise, analyse or otherwise convert data into usable information. The process may be automated and run on a computer. It involves recording, analysing, sorting, summarising, calculating, disseminating and...

 are allowed, and not necessarily in conjunction with other manufacturing

Manufacturing

Manufacturing is the use of machines, tools and labor to produce goods for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale...

 activities. Furthermore, income

Income tax

An income tax is a tax levied on the income of individuals or businesses . Various income tax systems exist, with varying degrees of tax incidence. Income taxation can be progressive, proportional, or regressive. When the tax is levied on the income of companies, it is often called a corporate...

 and property tax

Property tax

A property tax is an ad valorem levy on the value of property that the owner is required to pay. The tax is levied by the governing authority of the jurisdiction in which the property is located; it may be paid to a national government, a federated state or a municipality...

es payable to the Mexican Federal Government are minimal.
Some of the maquiladores pollute the Rio Grande

Rio Grande

The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...

.