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Unearthing the Evidence: How Soil Analysis will Revolutionize the National Stolen Properties Act

By Timur Tusiray


Less than one percent of the world’s archeological sites have been located or excavated, leaving the vast majority of humanity’s heritage open for discovery and exploitation by looters. This issue is not only relevant to Middle Eastern countries ravaged by conflict, but to areas around the world. For example, in China there are over a quarter-million known archeological sites, and it is reported that most have been looted to some extent. The sheer volume presents a unique challenge to those trying to prevent widespread looting by not only frustrating efforts to confiscate these looted objects, but also determining where they were looted. To further complicate matters, in the United States, criminal prosecution of those trafficking in cultural property hinges upon proving the actual provenance of these trafficked objects.

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Last month, the TED prize, a nonprofit forum for cutting edge ideas, was awarded to Dr. Sarah Parcak granting her $1 million to develop a project connected to her work in satellite archeology. Dr. Parcak is the founding director of the University of Alabama at Birmingham’s Laboratory for Global Observation, and through the use of satellite technology, has been able to track the increasingly destructive looting of archeology sites around the world. A pioneer in this new world of “satellite archeology,” Parcak has stated that she plans to use the money to continue her work in tracking, and hopefully preventing the widespread looting of cultural sites.

Parcak’s award is just another indication of the increasing awareness and action by the mainstream international community to protect cultural heritage. For more coverage on the subject, please read prior articles on the matter: here and here. However, what is truly unique to come from this development is Dr. Parcak’s recognition that satellite technology does not address the issue of tying a looted item to a particular site, but rather that, “someday digitized data on soil composition might be able to authenticate such matches.” (emphasis added).

That day may be soon upon us. With increasing technological advances in forensic soil analysis, and the recognition of its utility in combating the illicit market in cultural property, soil analysis can become a powerful tool. However putting the science aside, data from soil analysis could help alleviate the restrictive United States’ legal requirements for criminal prosecution of looters and the subsequent repatriation of looted objects through the National Stolen Property Act, giving a new tool to a traditionally convoluted and unwieldy test.

What is Soil Analysis?

Soil is a very complex combination of materials. Beyond the “parent rock” material, each sample has a unique composition of vegetation, flora and fauna, DNA of microbes, in addition to minerals the size and shape of sand grains. Soil analysis, in the context of assisting investigations into provenance, incorporates “new techniques in chemical, physical, biological, ecological and spatial analysis, coupled with informatics” to pinpoint areas in which the soil may have come, and to compare soil from those areas with the original soil sampling. This in turn helps investigators in site identification, site comparison and measurement for the eventual use as evidence in court.

Soil analysis is not a new technology, with the earliest example of a forensic soil comparison being documented in Berlin in 1856, and infamously having been considered by Sherlock Holmes in 1887 in, “A Study in Scarlet” to pinpoint the location of suspects. More recently, forensic soil analysis has been used by international organizations to combat the illicit trafficking of wildlife, and continues to be used on occasion by law enforcement agencies to assist investigations and solve crimes. However, the multi-disciplinary advances made in soil analysis has made progress from the realm of artful deduction into scientific process.

Application to Protecting Cultural Heritage

Soils can be a very potent type of trace evidence for linking an object to its original excavation site. Given the nature of the illicit market, in which objects may pass through several hands, and across many borders before being restored and cleaned, objects often retain the original soil from the site from which they were looted. It is typically not until the object reaches the final dealer that the object then gets cleaned in order to be sold. This traditional illicit market structure is also transforming, especially in cases involving the so-called Islamic State (“ISIS”), in which there is evidence of ISIS agents going directly to buyers in the West with these newly looted and soil encrusted objects.

There are already cases where soil analysis has been used to verify provenance of various cultural objects. For example, two Australian collectors were being investigated for possessing fossilized egg nests suspected of being looted from a Chinese site. The Australian collectors claimed the nests were not Chinese, but rather legal American fossils. Under Chinese law, fossilized dinosaur nests are protected, and both their sale and purchase are banned in Australia. To prove that they were illegally obtained, a soil analysis laboratory was hired, and compared the nest against soil samples from the various possible source areas for the nest. The lab found completely different mineralogy between where the collectors claimed the nest came from and the nest itself. They were subsequently convicted, and the eggs returned to China.

Soil analysis has many benefits for proving the provenance of an object. For example, trace soil may be so small as to be invisible, but with modern analysis, they can still yield meaningful results. Soil is easy to collect, and quickly analyzed. It can also be highly varied, and vast databases of soil types have already been catalogued. For example, in the U.S. alone there are more than 100,000 types collected, with attempts at digitizing and expanding the databases underway. Furthermore, the U.S. military has been collecting soil samples in the Middle East for decades now for various research reasons. Finally, unlike in wildlife crimes where DNA analysis is heavily relied on, cultural objects do not contain unique DNA identifiers, making soil a reliable alternative.

Finally, law enforcement officials working on wildlife crime, specifically that of ivory, sometimes find multiple soil samples on an individual tusk. Much like cultural objects, these elephant tusks were warehoused in various locations as they travel and exchange hands in the illicit market. Enforcement officials, utilizing these soil samples, were not only able to trace the tusk back to its original herd, but were able to determine which countries the tusks were trafficked through from each sample, and aggregating data and routes from multiple seized tusks are able to find “choke points” in the trade where a bulk of the objects travel through. This type of investigative work on wildlife crime has crossover into the world of looted cultural objects.

Of course there are still certain barriers to the widespread use of soil such as the cost, and limitations of access to soil databases around the world. However, with the increasing reliability of technology used in such analyses, along with the increasing call to repatriate looted objects, the importance of soil samples should only increase.

Why is this Important for Criminal Cases Brought in the United States?

The National Stolen Property Act (“NSPA”) is the central statute that has been utilized to prosecute individuals who transport stolen objects. It establishes a felony offense for knowingly transporting stolen objects in interstate or foreign commerce. This much maligned statute has the potential to be a vigorous tool to prosecute individuals dealing with looted objects in the United States due to its broad territorial application, however, it has been hamstrung by case-law interpreting the definition of “stolen property.” The increasing efficiency and spread of soil sampling may be the solution to make this statute relevant again.

Scope of the NSPA

The NSPA has broad territorial effect. In United States v. Schultz, the Second Circuit upheld a conviction of a well-known New York art dealer for conspiracy to receive property stolen in violation of a foreign government’s patrimony law. They further expanded that the objects need not be stolen in the U.S., and the owner of the object, nor the defendant have to be U.S. nationals (Schultz at 402). There only needs to be a nexus to the U.S. for the NSPA to be applicable. In the case of Schultz, the nexus was established when the objects were shipped to the United States.

Definition of Stolen Property

However, in United States v. McClain, the Fifth Circuit set out a stringent test (the “McClain Doctrine”) to determine when an object was considered “stolen.” In McClain, several American art dealers were convicted of selling stolen Mexican artifacts. The test the court laid out was that:

  1. Patrimony Law: The country from which the objects derives must have a clear law giving ownership of undiscovered objects in the state.
  2. Political Boundaries (Geographic and Temporal): And the objects in dispute must be shown to have come from the modern political boundaries of the state, after the effective date of the national ownership law.

This test was followed later in the Second Circuit in Schultz, and barring further case law diverging from it, is persuasive precedent for all jurisdictions applying the NSPA.

Much criticism has been leveled against the second prong of this test, saying that proving an object came from within the borders of a specific nation at a specific time is often difficult, if not impossible to prove. This is largely due to the fact that ancient civilization’s borders do not adhere to the borders of modern day states. For example, in McClain the defendants were accused of stealing certain pre-Columbian artifacts from Mexico. However, as was a point of contention in the case, the style of the artifacts in question could have been excavated not only in Mexico, but also Guatemala, Honduras, Panama, and Costa Rica. Looking at the Middle East, one can imagine the difficulty in proving the provenance of a looted Mesopotamian artifact, as the kingdom of Mesopotamia spanned across modern day Turkey, Syria, Iraq, Iran and some of Kuwait. Finally, without an eye witness at the looting, timing will always been in question. This is where the proliferation of accurate modern-day soil testing becomes invaluable.


As discussed above, soil sampling paired with aggregated data from satellite archeology, which can pinpoint the exact location and possibly the time of excavation, is no longer one of estimates, but of scientific fact. Dr. Parcak’s work highlights the importance of new scientific methods in combatting the illicit market in cultural objects. With the increasing scale and scope of looting occurring throughout the world, the United States must start utilizing such methods, especially that of soil analysis and sampling, in order to give new life to the NSPA.

Selected Sources

*About the Author: Timur Tusiray is a recent graduate of USC Gould School of Law, specializing in art and cultural heritage laws, human rights, and IP laws. He is currently an Orfalea-Brittingham Fellow at the Clinton Foundation. He may be reached at, or on twitter @TimurTusiray

Disclaimer: This article is being produced in the author’s individual capacity and does not reflect the views of his employer. This article is intended as general information, not legal advice, and is no substitute for seeking representation.