Harvard Law School’s Election Law Clinic (together with Selendy Gay Elsberg PLLC) filed this lawsuit to compel the Census Bureau to disclose important data about the Bureau’s 2020 products. For the first time, the Bureau used a method known as differential privacy by which random “noise” was added to the raw data. The Bureau then used another algorithm to further adjust the data after the application of differential privacy. This further adjusted data was disclosed to the public; the intermediate data — after the application of differential privacy but before post-processing — was not. It’s this intermediate data whose disclosure the Clinic’s lawsuit seeks. The intermediate data raises no privacy concerns (thanks to the application of differential privacy) but is vital to researchers interested in understanding any distortions or biases in the Bureau’s released 2020 products. Here’s some more information about the matter.
To analyze the potential impact of the 2020 DAS on accurate population demographics, including the effect of post-processing, Dr. Phillips requested access to the noisy measurements file underlying the published 2020 Census data and the 2010 Census demonstration data product. The files requested through the FOIA are important because biases in the data can harm communities’ ability to obtain their fair share of government funding and their ability to enforce their civil rights, including the right to equal political opportunity under the Voting Rights Act. Bias in census data also interferes with academic research in health, public opinion, and many other fields. Like much of political science research, Dr. Phillip’s public opinion research relies on census data as a key input to accurately characterize population-level estimates. With the planning of the 2030 Census underway, understanding the biases accompanying the Census’s current methods is pivotal to improving the accuracy of its data, ensuring privacy, and promoting civil rights under the Voting Rights Act.
The complaint details that Dr. Phillips is concerned that his research has been harmed because the post-processing phase may have systematically inflated the census-reported populations of sparsely populated and homogeneous areas while shrinking those with greater population density and diversity. This distortion in the 2020 Census would make the data less fit for use in Dr. Phillip’s research while also resulting in an inequitable distribution of political power and resources, likely harming racial minority groups.