The NCSL Blog


By Wendy Underhill

Right now—the second half of March—is when redistricting data should have been arriving in states, with the last delivery to be no later than April 1 as required by federal law. That’s not what’s happening, owing to delays in field operations for the census last year and more.

Alabama Attorney General Steve Marshall, along with Rep. Robert Aderholt, R-District 4, and two other Alabama voters have filed a lawsuit against the U.S. Census Bureau, specifically the bureau’s use of differential privacy. (Source: WSFA 12 News)It’s the “more” that surfaced in a case filed against the U.S. Census Bureau by Alabama’s attorney general, Republican Steve Marshall. His suit calls the bureau to task for missing the deadline and alleging the bureau’s decision to use differential privacy as its chosen statistical method for providing protection of respondents’ data is also unconstitutional.

The importance of protecting respondents’ data is not in question; confidentiality must be maintained by federal law for 72 years. The complaint questions whether the new system the bureau plans to use to protect respondents’ data, differential privacy, tips the balance between protecting privacy and producing usable data for redistricters.

(For those who don’t get their kicks from arcana, the bureau says differential privacy "is based on the cryptographic principle that an attacker should not be able to learn any more about you from the statistics we publish using your data than from statistics that did not use your data. After tabulating the data, we apply carefully constructed algorithms to modify the statistics in a way that protects individuals while continuing to yield accurate results.” It also offers an animated YouTube video made in collaboration with MinutePhysics to explain it.)

Does this case have legs? The schedule for court documents is compressed, and the plaintiff has asked that it go before a federal three-judge court whose ruling can be appealed straight to the Supreme Court.

“The Census Bureau is doing nothing more and nothing less than fundamentally altering how Census data is released, which will impact the ability of federal, state, and local governments and others to make effective use of the data,” says Jason Torchinsky, the lead attorney for the plaintiff.  “Redistricting, infrastructure funding, school funding, along with policy research and advocacy will be significantly impacted by the Census intentionally misreporting where populations are located.”

Kim Brace, president of Election Data Services, says the case “is asking the courts to weigh in on, what does it mean to protect privacy?”

Clark Bensen, of Polidata, says that question is substantive, and if the plaintiffs prevail and differential privacy is struck down, the bureau has indicated it does not have a “Plan B” ready to go.

If that were to happen, then census timing will be uncertain all over again. Of course, the words “census” and “uncertainty” have gone hand in hand these last few years. Which means states must continue to be flexible.

Here is NCSL’s explainer on differential privacy, an NCSL action alert from last year, and an easy-to-read report from Utah’s legislature on the bureau’s attempts to fine-tune differential privacy so far.

Wendy Underhill is director of NCSL’s Elections and Redistricting Program.

Email Wendy

Posted in: Census
Actions: E-mail | Permalink |

Subscribe to the NCSL Blog

Click on the RSS feed at left to add the NCSL Blog to your favorite RSS reader. 

About the NCSL Blog

This blog offers updates on the National Conference of State Legislatures' research and training, the latest on federalism and the state legislative institution, and posts about state legislators and legislative staff. The blog is edited by NCSL staff and written primarily by NCSL's experts on public policy and the state legislative institution.