Symposium: Supreme Court’s victory for disparate impact includes a cautionary tale
The Supreme Court decided a huge case today in favor of civil rights… and in favor of statistics! More nuance on the legal opinion can be found above and at many other posts at SCOTUSblog. But for computational purposes, I find these sections interesting:
the high court cabined disparate impact liability to those policies that pose “artificial, arbitrary, and unnecessary barriers.” That important qualifier may ultimately determine the outcome of this case on remand.
Does this mean that if we develop a model that has high utility and decreases disparate impact that the previous decision will be ruled unnecessary?
Most importantly, the full majority cautions that disparate impact liability poses “special dangers” that must be limited to avoid serious constitutional questions that might arise under the FHA if, for example, such liability were imposed based solely on a showing of a statistical disparity. This requires giving housing authorities and private developers adequate leeway to explain the valid interests their policies serve, an analysis that is analogous to Title VII’s business necessity defense. The Court emphasizes that policies are not contrary to the disparate impact requirement unless they are “artificial, arbitrary, and unnecessary barriers.” And the Court confirms that a disparate impact claim relying on a statistical disparity must fail if the plaintiff cannot point to a defendant’s policy causing that disparity. The Court views this crucial causality requirement as necessary to ensure that defendants (and courts) do not resort to the use of racial quotas.
There’s a lot here, but I think the big point is the importance of interpretable models. It sounds like the plaintiff must be able to interpret the defendant’s model in order to bring a valid claim. So we also need interpretability of models even without the right to examine or build the model ourselves! (Though I would argue that this is an unreasonable standard for the law to expect and that the burden should be on the defendant to provide an interpretable version of their policy. Perhaps it is?)
As today’s decision presages, the next challenge to “disparate impact” theory the Court will undoubtedly be forced to consider may prove to be a far more difficult one. As Justice Scalia noted in his concurrence in Ricci v. DeStefano, whether any statute that affirmatively requires race-based actions to remedy “disparate impacts” can be harmonized with the Fourteenth Amendment’s guarantee of equal protection is not an easy question to answer.
This is the question of if it’s possible to repair disparate impact without seeing its effect first. The assumption seems to be “no”, but we’ve actually shown a way of doing this (see paper here).
Another inspiring interpretation of the ruling can be found here. It argues that the ruling acknowledges “unconscious prejudice.” I.e., the statistics might show that a decision was discriminatory even if you didn’t mean it to be!