The Historian as Consultant and Expert Witness

Michael M. Brescia
Arizona State Museum
University of Arizona
March 2011

In addition to my research, teaching, and public outreach duties at Arizona State Museum, I am often called upon to serve as a consultant and expert witness in legal cases involving disputes over water rights and land use in Arizona and New Mexico. These cases generally raise questions about access to and control of natural resources as defined by the laws of Spain and Mexico prior to 1848, the year Mexico lost a substantial portion of its national territory to the United States.

In many high profile cases—both civil and criminal—expert witnesses are called upon to explain technical evidence and proffer their own opinions as to the veracity of the opposing side's arguments. Why would an historian be called upon? Most would be surprised to learn that historians play very important roles as expert witnesses in water rights and land use cases, as the U.S. court system struggles to understand the complex historical tapestry of Spanish laws, customs, and usages that continue to shape modern-day property rights and claims.

Myriad legal traditions fashioned the Spanish civil law of property before it was introduced to North America in the sixteenth century.  Historians point to influences from Roman, Canon, Islamic, and Visigothic law, all of which found a place in the evolving legal structures and cultural practices of late medieval and early modern Spain.  In theory, therefore, the historian (in my case one who specializes in colonial Mexico) is summoned as an expert witness to explain the Spanish civil law of property as it unfolded in Spanish North America, and to educate judges, special masters, and attorneys about its real significance to contemporary situations so that the courts can render well-informed rulings.

In a nutshell, what I do is assess pre-1848 Spanish and Mexican property rights in what we now call the Southwest in light of the Treaty of Guadalupe Hidalgo, the Gadsden Purchase of 1854, international law, and the U.S. historical experience, tracing the differences between public and private law and how such distinctions have been interpreted by Spanish and Mexican officials (and later by American jurists and scholars).

Judicial realities have fashioned an evocative context in the American Southwest where the Spanish civil law of property continues to operate in federal and state courts. The Treaty of Guadalupe Hidalgo, which ended hostilities between the United States and Mexico in 1848, and the Gadsden Purchase, obliged, and continue to oblige, the United States government to protect the property rights of those Mexicans and their successors-in-interest who suddenly found themselves residing north of the newly established international border.  The civil law of property that unfolded in the arid and semi-arid stretches of the Iberian Peninsula and later Mexico classified natural resources as property in ways that were quite distinct from Anglo common law, thus ensuring confusion after 1848 when disputes arose over the nature and scope of Mexican property rights in the territorial cession.

The historian who serves as an expert witness in the adjudication of water and land disputes in the U.S. Southwest, therefore, draws upon the statutory and case law from Spain and Mexico to show the primary legal principles that informed judicial decisions when places such as New Mexico, Colorado, and Arizona were part of the far northern frontier of New Spain.  Examples of legal codes and jurisprudence, as well as the application of the law that reflected local circumstances, reveal a strong colonial predilection toward equity and the common good rather than a zero-sum game approach to property rights and social harmony.

It was particularly exciting for me that the Arizona State Museum recently had the honor of exhibiting key original articles from the Treaty of Guadalupe Hidalgo. This was a rare opportunity for us to inform our community that this document, though 163 years old, still has an impact here in the American Southwest, resonating with numerous Hispanic and Native American communities that seek legal recourse to protect their natural resources and property rights.