First, the nationalization of petroleum. The Constitution of 1917, adopted by Carranza, and continued by de la Huerta and Obregon, definitely declares petroleum the property of the nation. In the grants of land made by the Spanish crown (the basis of all land titles in Mexico to-day), gold, silver and other metals were especially reserved as the property of the king, and in colonial times and since have been worked only by special permission or grant under “denouncement,” quite independently of the owner of the land. Neither coal nor oil was known to commerce in Spanish times, but in 1884, when the mining laws were revised, the Mexican government as inheritor of the rights of the Crown of Spain and retaining, as it did and does, the royal control over gold and silver, specifically stated that coal and oil belonged to the owner of the surface. This was confirmed later in the mining laws of 1892. In 1905, after oil was discovered and certain concessions for drilling had been issued to Sir Weetman Pearson (now Lord Cowdray), head of the Mexican Eagle Oil Company, an effort was made to have oil declared the property of the nation, like gold and silver, and thus subject to concession and denouncement. This was opposed by the American interests, which held no concessions. The issue was decided virtually unanimously by the Academy of Jurisprudence, and in the mining laws of 1909 the title to oil was definitely and unequivocably vested in the title to the surface soil. Until 1917, the vast development of Mexican oil fields went on apace, based on the old property rights and apparently safe from molestation. Carranza switched the matter completely around by the simple expedient of adding oil to the list of minerals which are national property and placing the new ruling in that famous Article 27 which contains most of the anti-foreign provisions of the new constitution. The Mexican defenses of this action are two. The primary thesis is that the subsoil has always belonged to the government, whether king or republic, and that it was beyond the power of ministers or courts or legislatures to alienate those rights. In other words, Mexico is only “taking back her own.” The opposition to this is on the basis of vested rights, on the long periods during which the owners of the lands had actually enjoyed possession of the subsoil, paying taxes on full valuations, and on the virtual obligation of contract of all Mexican governments to support developments under the laws of their predecessors.