The U.S. Equal Employment and Opportunity Commission (EEOC) in their UNIFORM GUIDELINES ON EMPLOYEE SELECTION PROCEDURES specifies:
A selection rate for any race, sex, or ethnic group which is less than four-fifths (4/5) (or eighty percent) of the rate for the group with the highest rate will generally be regarded by the Federal enforcement agencies as evidence of adverse impact, while a greater than four-fifths rate will generally not be regarded by Federal enforcement agencies as evidence of adverse impact.
This rule seems to work when selection rates are reasonably high. For example, if there are 70 male applications and 60 female applications, if 7 males are selected no fewer than 5 females should also be selected.
However, this principal seems to break down when selection rates are very low. for example, if 1000 males are eligible for a promotion and 3 are selected while 1000 females are also eligible for a promotion and 2 are selected, these selection rates would run afoul of this important piece of regulation.
Are there any resources or case law for how to interpret/apply the EEOC four-fifths rule when selection rates are very small?