What is the test for establishing that a city's decision-making body intended to discriminate on the basis of race?

The government need not prove that the [decision-making body] itself intended to discriminate on the basis of race in order to establish that the City acted with a racially discriminatory intent. In order to demonstrate a city's racially discriminatory intent, it is sufficient to show that the decision-making body acted for the sole purpose of effectuating the desires of private citizens, that racial considerations were a motivating factor behind those desires, and that members of the decision-making body were aware of the motivations of the private citizen[s]. United States v. City of Blackjack, Missouri, 508 F.2d [at 1185 n. 3]. Any other rule of law would permit a legislative body to place its official stamp of approval on private racial discrimination.