Census Bureau Will Release Files Sought by Harvard Law Clinic

The U.S. Census Bureau plans to release documents for academics to use to assess potential racial bias in redistricting, after the Harvard Law School’s Election Law Clinic requested the materials through the Freedom of Information Act, the agency announced March 27.

The Election Law Clinic — in conjunction with law firm Selendy Gay Elsberg PLLC — filed suit against the Census Bureau last October on behalf of Columbia University political science professor and department chair Justin H. Phillips, seeking to enforce a FOIA request that Phillips had filed in July 2022.

Academics hope to use the data files Phillips requested to determine whether data privacy techniques first used in the 2020 Census underrepresented people of color in redistricting processes. A group of more than 50 individuals, including professors, Ph.D. students, and industry professionals signed an open letter the Election Law Clinic sent to the Census Bureau in September 2021 requesting the files.

The Census Bureau declined to comment, saying that they do not respond to ongoing litigation and referring the request to the Department of Justice. The Department of Justice did not respond to a request for comment.

Differential privacy — the data privacy system used in the 2020 Census — aims to preserve information about groups of people while masking information at an individual level. The Census accomplishes this by randomly varying individual data points — referred to as adding noise — in a way that does not alter the data’s aggregate properties. A differentially private algorithm was applied to the raw census data to create a “noisy measurements” file.

In July 2021, Harvard Computer Science professor Cynthia Dwork, Election Law Clinic director Ruth Greenwood, and Harvard University Professor Gary King wrote in a Boston Globe op-ed that though the post-processing algorithm applied by the Census Bureau to the noisy measurements file is “quite helpful for some purposes,” it also “introduces biases that are difficult to correct for others” — a conclusion also reached by Harvard Government and Statistics researchers in a May 2021 study.

“Fortunately, making available the noisy measurements file is an easy solution and the key to ensuring that analysts can easily use the data appropriately,” the op-ed stated. “That file will allow analysts to correct for all biases (with straightforward statistical methods easy to make available to all) and to offer accurate margins of error.”

In an interview after the Census Bureau’s announcement, King said that “now for the first time, we can find out” if the 2020 Census contained biases. To do so, he hopes to use statistical techniques to determine “how the different racial groups are voting.”

Greenwood said the noisy measurements would allow researchers to assess potential concerns over bias in the 2020 Census.

“It will give us some sense of if there are places that are undercounted. There was some belief that, perhaps, Native American communities in tribal areas — because of the low population density — would end up appearing to be undercounted in the final census and that may have consequences for federal funding but it could also have consequences for representation,” she said.

Third-year law student Delaney I. Herndon, who is in her third semester at the Election Law Clinic, spoke about the nature of student involvement in the case.

“I was not involved on the project last semester but joined the team this semester as we were preparing for a potential motion for summary judgment, and I’ve been working with the clinic on the case as we’ve been interfacing with the Census Bureau and opposing counsel this last semester,” she said.

Herndon, who plans to clerk after Law School, said that she “hopes to work in the election democracy voting space long term.”

Despite the Census Bureau’s March 27 announcement, Greenwood said “they haven’t set a date” for the release of the noisy measurements.

“In the rest of the case, we can still seek to have a judge set a date for the release of the 2020 file, and so that isn’t resolved yet,” Greenwood said.

—Staff writer Neil H. Shah can be reached at neil.shah@thecrimson.com. Follow him on Twitter @neilhshah15.