I suppose its not far from the SCOTUS 1st Amendment cases of porn/obscenity, they can't quite define it, but they'll know it when they see it.
Grutter v. Bollinger, 539 U.S. 306 (2003) (link: https://supreme.justia.com/cases/federal/us/539/306/)
>The requirement that all race-conscious admissions programs have a termination point "assure[s] all citizens that the deviation from the norm of equal treatment of all racial and ethnic groups is a temporary matter, a measure taken in the service of the goal of equality itself." Richmond v. J. A. Croson Co., 488 U. S., at 510
>But such measures, the Convention instructs, "shall in no case entail as a consequence the maintenance of unequal or separate rights for different racial groups after the objectives for which they were taken have been achieved." Ibid.; see also Art. 1(4) (similarly providing for temporally limited affirmative action); Convention on the Elimination of All Forms of Discrimination against Women, Annex to G. A. Res. 34/180, 34 U. N. GAOR, 34th Sess., Res. Supp. (No. 46), p. 194, U. N. Doc. A/34/46, Art. 4(1) (1979) (authorizing "temporary special measures aimed at accelerating de facto equality" that "shall be discontinued when the objectives of equality of opportunity and treatment have been achieved").