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Researchers tap AI to identify racial restrictions in millions of property records

SIEPR鈥檚 Daniel Ho and fellow researchers trained a large language model that paves the way for faster, more accurate compliance with California鈥檚 anti-discrimination law.

When Dan Ho purchased a home in Palo Alto, he recounts, 鈥淲e had to sign papers that said that the 鈥榩roperty shall not be used or occupied by any person of African, Japanese or Chinese or any Mongolian descent,鈥 except for the capacity of a servant to a White person.鈥

鈥淚t was a stunning testament to housing discrimination in the area and it鈥檚 been constitutionally unenforceable since 1948,鈥 said Ho, the William Benjamin Scott and Luna M. Scott Professor of Law and Director of RegLab at the 成人大片 Law School, and a senior fellow at the 成人大片 Institute for Economic Policy Research (SIEPR) and 成人大片 Institute for Human-Centered Artificial Intelligence (HAI).

Despite the Supreme Court such clauses unenforceable, racially restrictive covenants still litter deed records across the country.

In 2021, California that required the state鈥檚 58 counties to create programs to identify and redact deed records that include racial covenants.

But the new law also posed a daunting task: Santa Clara County alone has , totaling 84 million pages, dating back to 1850. 鈥淧rior to this collaboration, our team manually read close to 100,000 pages over weeks to identify racial covenants,鈥 Assistant County Clerk-Recorder Louis Chiaramonte said, 鈥渁nd it was a challenging undertaking.鈥

To comply with the law, some California counties contracted with commercial vendors. , for instance, hired a company for $8 million to conduct this scan over seven years. In other jurisdictions, teams of citizens have valiantly crowdsourced these efforts with thousands of volunteers pouring over deed records. But not all jurisdictions have such resources.

The County of Santa Clara, home to Silicon Valley, approached it differently. 成人大片鈥檚 partnered with the County to use the power of AI 鈥 and large language models, specifically 鈥 to assist in this monumental task.

鈥淭he County of Santa Clara has been proactively going through millions of documents to remove discriminatory language from property records,鈥 said Chief Operating Officer Greta Hansen. 鈥淲e鈥檙e grateful for our partnership with 成人大片, which has helped the County substantially expedite this process, saving tax-payer dollars and staff time.鈥

The team, led by 成人大片鈥檚 RegLab and including HAI affiliates and Princeton Professor Peter Henderson, curated a collection of racial covenants from various jurisdictions in the country and trained a state-of-the-art open language model to detect racial covenants, with almost perfect accuracy. 鈥淲e estimate that this system will save 86,500 person-hours and cost less than 2 percent of what comparable proprietary models would have,鈥 said co-lead author Faiz Surani, a fellow with the RegLab. The team zoomed in on 5.2 million deed records between 1902-1980, the period most at issue.

The team also figured out a way to cross-reference historical maps to locate most of these properties. They matched textual descriptions of maps (e.g., 鈥淢ap [that] was recorded . . . June 6, 1896, in Book 鈥業鈥 of Maps at page 25.鈥) to administrative records in the Santa Clara County Surveyor鈥檚 Office to geolocate tracts. 鈥淥f all the items coming out of the state law, we thought that mapping could have been nearly impossible,鈥 Chiaramonte said.

These maps revealed extraordinary insights into the evolution and diffusion of racial covenants in Santa Clara County:

1) The team estimated that one in four properties in Santa Clara County were subject to racial covenants as of 1950.

2) Only 10 developers were responsible for a third of the identified covenants, suggesting that developers had a lot of say in how Santa Clara County was constructed.

3) Racial covenants excluded African Americans at the same rate as Asian Americans, even when African American residents were less than a tenth the size of the Asian American population.

4) The team found a striking instance of a San Jose-owned cemetery that included burial deeds only for 鈥淐aucasians.鈥 This goes against the conventional historical account that racial covenants were used only between private parties after the Supreme Court banned state-based racial zoning.鈥淲e believe this is a compelling illustration of an academic-government collaboration to make this kind of legislative mandate much easier to achieve and to shine a light on historical patterns of housing discrimination,鈥 said co-lead Mirac Suzgun, a JD/PhD student in computer science. Chiaramonte agreed: 鈥淭his collaboration paved a new path for how we can use technology to achieve the momentous mandate to identify, map, and redact racial covenants. It reduced the amount of time our team needed to review historical documents dramatically.鈥

Clusters of racial covenants as captured from an interactive map of modern-day Santa Clara County. Some of the largest and most notable racially restricted developments are shown in red. See the research paper to access the interactive map.

鈥淲e believe this is a compelling illustration of an academic-government collaboration to make this kind of legislative mandate much easier to achieve and to shine a light on historical patterns of housing discrimination,鈥 said co-lead Mirac Suzgun, a JD/PhD student in computer science. Chiaramonte agreed: 鈥淭his collaboration paved a new path for how we can use technology to achieve the momentous mandate to identify, map, and redact racial covenants. It reduced the amount of time our team needed to review historical documents dramatically.鈥

The team has released the paper at and is making the model available to enable all jurisdictions faced with this task to identify, redact, and develop historical registers of racial covenants more effectively.

This story was October 17, 2024 by 成人大片 Law School. 

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