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Data Produced By Cell Phones Not Sufficiently Accurate to Use for Coronavirus Contact Tracing, Says ACLU

David Jelke



Screenshot of the ACLU's Jay Stanley at May 2017 event hosted by Lexington Institute

April 10, 2020 - Data produced by cell phones is “not sufficiently accurate to be used for contact tracing,” according to Jay Stanley, senior policy analyst at a Wednesday press briefing by the American Civil Liberties Union.

Contact tracing is the practice of using data to infer the likelihood that an individual or a group of neighbors has been in contact with someone who has tested positive for the coronavirus. Cell phones produces location data that potentially allow governments to perform contact tracing.

Stanley outlined three problems with mass data collection that the ACLU has identified:

  • First, “Data on individuals’ locations is not accurate enough for automated contact tracing.”

Cell tower location data can’t tell you how close two phones are to each other. GPS has a margin of error of five to 20 meters on a clear day and doesn’t work when you’re indoors.

Wi-Fi tracking is simply used to supplement cell towers and GPS. And QR codes are not widespread enough in the U.S. to be useful like they were in China, where citizens must scan a QR code when entering buildings, buses, and taxis.

  • Second, the algorithms that buttress contact tracing are not likely to be reliable.

This one is a little tricky to understand, so a recent example in the news might help elucidate the issue. In Israel, a contact tracing algorithm flagged an Israeli woman simply for waving at her infected boyfriend from outside his apartment building and was resultingly issued a quarantine.

“Such a system is likely to make many such mistakes,” a white paper released by the ACLU stated. The white paper noted that “human life is messy, complicated, and full of anomalies.”

  • Third, “the data is fragmented and may be biased.”

The white paper makes the point that “no single, centralized party holds the location data generated by Americans.” Instead, it is divvied up amongst what the ACLU refers to as “an essentially corrupt ecosystem” of companies that hide tracking capabilities in apps.

Big tech companies like Google and Facebook may also provide reach, but their location database only covers a minority of their users and is therefore not representative and may leave out entire populations.

In addition to the technical feasibility of contact tracing in the U.S., the ACLU expressed reservations about the protection of data privacy.

Jennifer Granick, surveillance and cybersecurity counsel at the ACLU, said that South Korea “did not do a good job” in anonymizing data and resultingly the data may have suffered from a “social humiliation” backlash that undermined the integrity of the data collection efforts and certainly the privacy rights of its citizens.

She added that data collection “should be limited to the public health crisis” and that proper regulatory oversight will be needed to actually make that happen. However, with the right set of safeguards in place, Granick acknowledged that “privacy and effectiveness are actually complementary and not contradicting.”


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