Lerdo Law in the context of "La Reforma"

The Reform War (17 December 1857 – 11 January 1861) or War of Reform (Spanish: Guerra de Reforma), also known as the Three Years' War (Spanish: Guerra de los Tres Años), and the Mexican Civil War, was a complex civil conflict in Mexico fought between Mexican liberals and conservatives with regional variations over the promulgation of Constitution of 1857. It has been called the "worst civil war to hit Mexico between the War of Independence of 1810–21 and the Revolution of 1910–20". Following the liberals' overthrow of the dictatorship of conservative Antonio López de Santa Anna, liberals passed a series of laws codifying their political program. These laws were incorporated into the new constitution. It aimed to limit the political power of the executive branch, as well as the political, economic, and cultural power of the Catholic Church. Specific measures were the expropriation of Church property; separation of church and state; reduction of the power of the Mexican Army by elimination of their special privileges; strengthening the secular state through public education; and measures to develop the nation economically.

The constitution had been promulgated on 5 February 1857 was to come into force on 16 September 1857. There was intense opposition from Conservatives and the Catholic Church over its anti-clerical provisions, but there were also moderate liberals, including President Ignacio Comonfort, who considered the constitution too radical and likely to trigger a civil war. The Lerdo Law forced the sale of most of the Church's rural properties. The measure was not exclusively aimed at the Catholic Church, but also Mexico's indigenous peoples, which were forced to sell sizeable portions of their communal lands. Controversy was further inflamed when the Catholic Church decreed the excommunication of civil servants who took a government-mandated oath upholding the new constitution, which left Catholic civil servants with the choice of losing their jobs or being excommunicated.

Miguel Lerdo de Tejada (July 6, 1812 – March 22, 1861) was a Mexican statesman, a leader of the Revolution of Ayutla, and author of the Lerdo Law, extinguishing the right of corporations, including the Roman Catholic Church and indigenous communities, from holding land.

Born in the port of Veracruz, Veracruz, both he and his younger brother, Sebastián Lerdo de Tejada, became leaders of Mexico's Liberal Party. As the president of the ayuntamiento (city council) of Mexico City in 1852, Miguel Lerdo de Tejada proposed initiatives on public education, transportation, public health, and budgetary reforms. Lerdo served Antonio López de Santa Anna in his final term as president (1853–55) and then as the Treasury Secretary under liberal president Ignacio Comonfort following the successful implementation of the Plan de Ayutla. In 1856, Miguel Lerdo de Tejada initiated the Ley de Desamortización de Fincas Rústicas y Urbanas (Disentailment of Rural and Urban Properties Law), commonly known as the Ley Lerdo, which called for the forced sale of most properties held by the Roman Catholic Church in Mexico, common lands of indigenous communities, and by municipal and state governments. The Church could retain only the buildings it used for its operations (churches, monasteries, seminary buildings); governments could keep only government offices, jails, and school buildings. Other property, which had been used to generate income for the Church and for local governments, was to be sold with the proceeds going into the national treasury. Because of the disruptions of the War of Reform (1858 - 1861) and the French Intervention (1862 - 1867) that wracked Mexico, few properties were actually sold as a direct result of the Ley Lerdo. Most of the "disruptions" attributed to that law actually occurred later, under legislation passed during the regime of Porfirio Díaz (1876 - 1911), but took their legal foundation in the Ley Lerdo.