"We'll enforce the laws when they're broken" has theoretical problems in its own right, but let's take a step back here. Because when you come down to it, we, um, don't.
UNC Law Professor Eric Muller has spectacular post on a 1996 Supreme Court case called U.S. v. Armstrong, which significantly raised the bar for when a defendant can force the government to turn over evidence pointing to racism in its practices.
The defendants in the Armstrong case had come forward with some evidence -- not a ton, but some -- that the US Attorney in Los Angeles was singling out blacks for crack cocaine prosecutions in federal court. It was enough evidence to persuade the federal trial judge to allow the defendants discovery of some material in the prosecutor's files and records. But the Supreme Court shut that discovery down, pooh-poohing the evidence of racial discrimination that the defendants had managed to come up with and setting an absurdly high burden of proof for defendants trying to prove discriminatory prosecution.
Muller then links to a similar case currently moving through Georgia courts. Relying on Armstrong, the Court denied the defendant's request for discovery into the Prosecutor's motives. So the ACLU sprung for the $60,000 necessary to fund the study privately. Here's what they found:
"Of 629 convenience stores in the six-county area in the sting, 80 percent are owned or operated by whites, according to the A.C.L.U.'s court filing, but fewer than 1 percent of the stores in the sting are white-owned or operated. The filing said the clerk at the only white-operated store was known widely as a methamphetamine addict whose husband was in prison for making the drug. None of the Indians charged are accused of using or making methamphetamine."
This is just a mind-blowing disparity that seems to be prima facia proof of racist intent. But because of Armstrong, there was no legal right to this information, it never would have come out if it weren't for the ACLU offering its resources. As Muller notes, most poor defendants don't have groups willing to throw $60,000 at their plight. Because our legal system pretends that racism is a smaller problem than it is, it virtually guarantees that the very real racist practices and policies in our criminal justice system will continue unchecked by law. Hence, even "when it happens," we don't "deal with it", we just figure out new ways of rationalizing it.