A third and final Mexican statute of April 4, 1837, repeated the stipulations of the preceding two laws, once again banning slavery and reaffirming the right to compensation for any master despoiled of his human property upon entering Mexico.89 The passage of three nearly identical mandates betrayed the Mexican government’s failure to effectively enforce the first two. The country’s vast territorial domain made it hard for the government to uphold such regulations in its sparsely populated frontier provinces, especially New Mexico, a difficulty that American lawmakers came to appreciate in later years. Continuous reverberations in governmental leadership, an omnipresent threat of political coups, and financial insolvency made it tough for the Mexican national government to exert any meaningful effort toward the enforcement of antislavery provisions.
Congressional dialogue on the validity of Mexican laws during the 1848–1850 sessions reflected the rampant sectionalism that fueled such debates, with all rationality sometimes being thrown to the wind during the course of rhetorical exchanges. Because Mexico’s statutes prohibited slavery, Northerners voiced strong support for their continuance and sought to incorporate them into a new set of regulations for New Mexico. Conversely, Southerners denied that the laws remained applicable. John Berrien summarized his section’s position when stating that earlier laws, “with whatever authority they may have been enacted while California and New Mexico were a part of the Mexican republic, ceased instantly upon their transfer to the United States.”90 Had Mexico’s laws upheld the institution of slavery, Northern and Southern positions on the matter would no doubt have been reversed.
Northerners cited legal precedent in support of retaining the preexisting laws of conquered territories, alluding to instances in which the U.S. Supreme Court ruled that civil and municipal codes relating to property ownership in ceded foreign land remained in force until government officials annulled or replaced them. Senator Cooper mentioned seven different court cases that established this legal standard.91 The primary basis for his argument emanated from an 1828 Supreme Court case in which Chief Justice John Marshall addressed the issue as it pertained specifically to territorial acquisitions. Upon reverting to American sovereignty, a ceded territory dissolved all formal relations with its former country and came under the jurisdiction of the United States. Marshall explained that the transfer of land from one nation to another involved a complementary and obligatory shift in allegiance on the part of those residing there but acknowledged that any law regulating “the intercourse and general conduct of individuals,” including property rights and, by extension, slavery, would remain in effect until modified “by the newly created power of the state.”92
In other words, upon the acquisition of foreign territory, the existing law of the land continued in full effect until the conquering nation abrogated or amended it. Northern abolitionists used this ruling to argue for the continuation of Mexican antislavery laws, pointing out that no new edicts had yet been enacted to replace the old ones. According to Southern logic, however, this argument did not apply to the present situation because the Supreme Court ruling pertained to civil laws involving “the intercourse between citizen and citizen” and therefore had no impact on political mandates involving slavery.93 Senator Calhoun conceded that foreign municipal laws proven to be consistent with the American political system might remain unchanged, but he insisted that this should have no impact on slavery in New Mexico. Based on his interpretation of preexisting Mexican municipal law, Calhoun concluded that “the peonage system would continue, but not to the exclusion of such of our citizens as may choose to emigrate with their slaves or other property.”94 In Calhoun’s eyes, the Northern argument contradicted itself inasmuch as Mexican statutes prohibited chattel slavery but upheld peonage, which in principle and practice was merely a modified form of involuntary servitude. Because slaves were not considered citizens, Northerners countered that Mexico’s civil and municipal laws could not, under the U.S. Constitution, continue to regulate slavery in New Mexico. The entire debate hinged upon one question: Did a law regulating slavery constitute a “civil or municipal law” or a “public or political law”? If the former, then Mexican legislation could not remain in effect beyond the moment of American conquest.
Speaking to the House of Representatives on July 29, 1848, Richard Donnell of North Carolina announced once again that Mexican law abolished enslavement and proclaimed in no uncertain terms that “African slavery, as it exists in the Southern States, was forbidden in that territory at the time it became, by cession, a part of our country.”95 Senator Benton, who claimed to have been averse to slavery in principle since early adulthood, concurred in the view that Mexico’s antislavery provisions had not been automatically repealed when the southwestern domain shifted to American jurisdiction. In New Mexico and California, he pointed out, slavery had already been abolished at the time of the American conquest and could be reintroduced there only if Congress passed a new law to that effect.96
Addressing political colleagues on July 8, 1850, Senator Truman Smith offered a detailed description of slavery laws in New Mexico, beginning his diatribe with the straightforward comment that slavery had been prohibited there prior to the region being ceded to the United States. “If the ordinances and laws of Mexico abrogating slavery do not continue, yet it may be assumed that there is no law authorizing it,” he reasoned, “and this is just as serious an obstacle to the introduction [of slavery] as a positive law forbidding it.”97 Because Mexican statute applied to the region at the time of the American conquest, Smith contended that those laws remained valid and enforceable, and by simply recanting such edicts Congress could not “reintroduce slavery” without passing an entirely new law to that effect.98
Still other Northerners feared that previous Spanish and Mexican mandates outlawing slavery would prove insufficient in preventing its eventual extension into the Southwest, demanding that Congress enact additional measures to ensure that black men and women could never be taken to those territories as slaves. Representative Marsh again questioned the validity of Mexico’s laws, warning fellow Northerners about the veracity of such abolitionist doctrine and suggesting that U.S. courts would be unlikely to recognize another nation’s legal codes. Skeptical of what judges might rule in the event of litigation, he cited this ambiguity as sufficient justification for the enactment of additional measures outlawing slavery in the Southwest.99
Marsh focused on Mexico’s 1824 federal constitution, which he claimed had regulated slavery but not abolished it entirely, because the document banned involuntary servitude only in that republic’s states. New Mexico and Alta California had been provinces—similar to territories in the U.S. body politic—and it remained a matter of interpretation as to whether the Mexican constitution had indeed outlawed slavery there along the same lines as the more southerly states. Subsequent laws passed in 1829 and 1837 were also questionable in their ultimate effect, in part due to civil and social unrest in that country. The general instability of Mexico’s government made it difficult for American lawmakers to determine whether or not that country’s congressional bodies even had the power to pass acts that superseded the 1824 constitution.100
These legal loopholes jeopardized the Northern movement to ban slavery in the Southwest. “Though slavery may have been