The case In re Navy Chaplaincy involves a group of current and former non-liturgical Protestant chaplains in the U.S. Navy who sued the Department of the Navy, alleging that it discriminated against them on the basis of their religion by using quotas and religious preferences in their promotion decisions. The chaplains argued that the Navy's promotion practices discriminated against candidates who had different faiths than the chaplains on the promotion selection board or the Chief of Chaplains, who served as the selection board president. Specifically, the claimants said that the small size of the selection board, combined with the board's secret voting process, led to more promotions for Catholics and liturgical Protestants than for non-liturgical Christians.
To attempt to prove that the Navy's promotion practices were applied unfairly, the chaplains presented evidence showing that the difference between the 83.3 percent promotion rate for candidates of the same denomination as the chief of chaplains and the 73.3 percent promotion rate for candidates of different denominations was statistically significant.
The Court of Appeals rejected the chaplains' claim for two reasons. First, the court observed that the magnitude of the difference in promotion rates "does not remotely approach the stark character of the disparities in Gomillion or Yick Wo," two precedents that set the threshold for allowing statistical impact alone to establish an equal protection claim. Second, the court criticized the chaplains' statistical methodology, stating:
"Assuming arguendo that the methodology for determining statistical significance is reasonable, the finding does little for our analysis. ‘Correlation is not causation.' Statistical significance, assuming it has been shown, indicates only a low probability for one possible cause of the alleged disparities — random chance. The chaplains have made no attempt to control for potential confounding factors, such as promotion ratings, education, or time in service. Thus the label ‘statistically significant' does nothing to elevate [the chaplains'] figures into the realm of Yick Wo or Gomillion."
On Oct. 6, the U.S. Supreme Court denied the chaplains' petition to review this decision. Thus, it stands as the final word on the lack of sufficiency of the chaplains' statistical proof.
In re Navy Chaplaincy provides a potent reminder about the difference between the thresholds for statistically and legally meaningful empirical findings. It is well-established that the magnitude of a relevant difference, and not merely its statistical significance, should be considered when determining whether a plaintiff has met his or her burden of proof (e.g., Bregant & Robennolt, 2012). Courts do recognize that the magnitude of the difference in treatment of two groups can be so great that the only plausible explanation for the difference is discrimination. For example, in Yick Wo, a city board denied licenses to 100 percent of all Chinese applicants, but denied only one of 80 applications from other applicants. In Gomillion, all but five African-American voters — but no white voters — were excluded from a voting district. When the magnitude is not so great, however, parties must do more than establish a statistically significant disparity: The statistics must be supplemented with other evidence showing intent to discriminate.
It is also well-established that statistical evidence can be proof of discrimination if major confounding factors are accounted for. In Bazemore v. Friday (1986), the Supreme Court explained that although the omission of some variables from a regression analysis may make the analysis less probative than it might otherwise be, claimants "need not prove discrimination with scientific certainty," but rather by a preponderance of the evidence taken as a whole. The chaplains' failure to account for major confounds, combined with their failure to provide other evidence of discrimination, doomed their case.
