Digital borders within cities: How technology is undermining sanctuary protections for migrants

Sanctuary cities aim to ensure that city residents without secure immigration status can access essential services, such as health care, education and housing, without fear that their personal information will be shared with immigration authorities. But new research from Toronto Metropolitan University (TMU) warns that digital technologies may be quietly eroding these protections.

The research, co-led by Graham Hudson, the associate dean at TMU’s Lincoln Alexander School of Law and an expert in immigration law and governance, is the first of its kind to examine how digital surveillance and data-sharing practices are reshaping sanctuary city policies that were designed to limit cooperation between local and national governments. The researchers focused on how government responses to the COVID-19 pandemic in the U.K. and Canada impacted migrants’ rights.

A concerning shift in sanctuary protections

Drawing on in-depth fieldwork within community organizations and over 100 interviews with advocates, lawyers, doctors and government officials, the researchers compared migrants’ experiences in Sheffield, U.K. and Toronto, Canada. These were the first cities in their countries to adopt sanctuary policies. They found that digital systems have made it easier for national authorities to access local data networks that were once kept independent, blurring the line between public services and immigration control.

During COVID-19, governments expanded digital surveillance to track infections and deliver vaccines, creating new flows of personal data between local and national systems. In Ontario, for instance, police were temporarily granted access to provincial COVID-19 data, including health card information, until legal challenges forced the government to reverse course.

Professor Hudson and his collaborators called this “hostile data-sharing” – when information collected for one purpose, such as health care, is repurposed for immigration enforcement. “The number one reason why non-status migrants don’t access services to which they’re entitled is because they’re afraid that if they provide information about themselves to get health care, that information will be shared with immigration authorities,” he said. “So, they just don’t do it at all.”

Innovation and resistance

The research also found examples of adaptation and resistance. In Toronto and Sheffield, community organizations and health providers developed “digital sanctuary” practices. These included parallel databases or pseudonym systems that allowed residents to receive vaccines or basic health care without revealing immigration status.

“These were creative workarounds,” professor Hudson said. “They showed that cities are learning to adapt by building what we call non-interoperable data systems, or, in other words, systems that don’t automatically share personal information with higher levels of government.”

Yet these strategies come with challenges. Limiting data collection can make it harder for cities to deliver effective services or understand the needs of migrant communities. Reliance on private tech companies to manage information raises new concerns about accountability, transparency and corporate control.

The research also found key differences between the two countries. Canada’s federal system, which divides powers between national, provincial and local governments, offers municipalities more room to safeguard privacy. In contrast, the U.K.’s centralized system allows national authorities to override local sanctuary efforts more easily.

Technology, privacy and equity

Professor Hudson cautioned that digital systems have made it increasingly difficult for any jurisdiction to maintain sanctuary protections. “Once data is collected and stored digitally, it’s very difficult to control how it’s used,” he said. “That’s true for migrants, but it’s also a lesson for all of us.”

The growing interconnection of population databases has immediate consequences for migrant rights, professor Hudson noted. It also raises broader questions about privacy, equity and the role of technology in everyday governance. “We often think of digital innovation as neutral or efficient,” he said, “but technology can reinforce existing inequalities if we’re not careful about how it’s designed and used.”

This research calls for new forms of “digital sanctuary,” including data practices and infrastructures that prioritize safety, anonymity and trust. As professor Hudson explained, “If we want sanctuary cities to be more than symbolic, we have to ensure that technology works for protection, not surveillance.”

Read “Digital internal bordering: Surveillance, data sharing, and the fate of sanctuary cities (external link, opens in new window) ” in the Journal of Ethnic and Migration Studies.

The research mentioned in this article was supported in part by a Social Sciences and Humanities Research Council Insight Grant.