As an outpost of the kingdom of New Spain, the province of Texas shared with Mexico the basic law of the parent sovereign, that of Castile. This law went essentially unchanged during the tumultuous fifteen years of Mexican Texas (1821–36), but after the Texas Revolution, the Republic of Texas adopted the law of England in preference to that of Spain. Three areas of law were excepted from the wholesale adoption of English law in Texas: certain procedural rules affecting trials, the law affecting land titles and certain water rights, and a large body of rules affecting family relationships. In spite of severe antagonism to Spanish and Mexican government, the predominantly Anglo-American colonists of Texas found in the prevailing legal system a number of elements better adapted to their conditions than Anglo-American legal institutions under which they had been reared in the United States. Anglo-American judicial procedure was inordinately complex and operated through two different sets of courts with different rules-those of law and equity. The Castilian legal system functioned very satisfactorily with a unitary judiciary. This system appealed to the frontiersmen, and they perpetuated it. Castilian court rules of pleading as understood on the frontier were simple and straightforward, as compared to the complicated English forms of action and pleadings, and so these Spanish rules were also retained. But after the Civil War, with a great influx of common-law lawyers and teachers trained in the Anglo-American system, this simplicity of procedural rules became more and more theoretical. The Castilian principle of venue of lawsuits was also favored. Whereas the English rule was that a person was sued in the court of the locality where the facts giving rise to the dispute occurred, the Spanish rule required that a person be sued where he lived, for the convenience of the defendant. Though that rule had a number of original Castilian exceptions that were retained, it acquired a great many more in the years following that tended to impede its effectiveness. The Castilian tradition also provided a model for a system of probate administration that is much simpler than the English system. The Texas institution of an independent executor, seemingly modeled on the Castilian albacea universal, provides for great flexibility and reduced cost in probate practice.
It is a basic rule of international law that when sovereignty changes, general law does not change until specifically altered by the new sovereign, and titles to land already acquired will not be interfered with. Hence, land-title law was not varied by the change from Mexican to Texan sovereignty except insofar as the previous holders of land who had espoused the Mexican cause had their lands declared forfeited. An anomalous result of continued application of the Spanish doctrine to land grants made before the act of January 20, 1840, and those made thereafter is that different rules may apply to adjacent tracts depending on the origin of the grant. Along the seashore, for example, where the shore is flat, a common-law grant may extend farther toward the ocean than an adjacent Spanish law grant because of the different system of measuring the coastal boundary. With respect to grants along rivers, there is also a difference. Grants made under Hispanic rules extend only to the bank of a navigable stream, as the sovereign was the owner of the riverbed. Subsequent common law grants extend to the center line of a navigable stream. If the owner of a Hispanic grant should own both banks, however, the effect of the Small Act of 1929 is that he will own the bed of the stream as well as the banks. The law applicable to Spanish grants is also much more restrictive as to irrigation rights, since Spanish grants do not carry such rights unless specifically granted.
The most significant residuum of Spanish law is in the area of family relationships. Adoption was unknown in English common law. Its comparatively early institution by statute in Texas (1850) is generally attributed to the Spanish legal tradition. The law of matrimonial property is also heavily influenced by the Spanish tradition. The Anglo-American frontiersman found the idea of common ownership of the gains of marriage between husband and wife much more agreeable to his society than common-law principles (see COMMUNITY PROPERTY LAW, and SEPARATE PROPERTY LAW). Protection of certain land and tools of husbandry and trade from creditors' claims was also appealing to him, as opposed to the creditor-oriented rule of common law (see HOMESTEAD LAW). This adoption of Hispano-Mexican principle has spread from Texas with varying degrees of liberality to other states. Texas law also followed the Hispanic model of allowing the husband to protect the home by giving him the right to kill his wife's paramour without punishment. See also LAND GRANTS, LAW, MEXICAN COLONIZATION LAWS, and WATER LAW.