Pacific Legal Foundation has a nice write-up here.
There are two types of discrimination recognized by our various civil rights laws: disparate treatment and disparate impact. The former is conscious, intentional discrimination. The latter is unintentional, and is demonstrated through statistical disparities. Here on the Liberty Blog we have often posted on various absurd applications of disparate impact theory. We have also notedhow the Obama Administration is trying to inject disparate impact into nearly every facet of American life. Disparate impact is a pernicious doctrine that forces racial balancing, hurts business, and violates the Equal Protection Clause.