In 1972, the Civil Rights Act of 1964 was amended to apply to public employers, including school districts, making the hiring of black teachers almost a necessity in order to avoid liability.

]"[1]: 304  Hazelwood appealed to the Supreme Court to review the Court of Appeals decision, arguing that the relevant labor market statistics should not include the St. Louis numbers, because that city had imposed very strict hiring guidelines to help overcome past racial discrimination.

[1]: 311 The Supreme Court decided that, in this case, the proximity of the questionable hiring statistics to the application of Title VII to public employers was very relevant.

The primary reason for the ultimate decision of the Court was that "pre-Act" hiring practices, that were perfectly legal under Title VII until the 1972 amendment, might have caused the statistical disparities in question.

The Teamsters decision was very important in the evolution of disparate impact jurisprudence, and made it much easier for the victims of discrimination to bring cases against their employers.