The court was ruling on the case of a Maryland man whose DNA was collected after his 2009 arrest for second-degree assault, whereupon it was matched to a rape almost six years earlier. A knee-jerk reaction might be: Good, they got the right man. But as Blackstone noted, a just society has more important goals than simply apprehending the guilty.
Justice Antonin Scalia, who uncharacteristically sided with a liberal minority in the 5-4 decision, put it well in his dissent: "Solving unsolved crimes is a noble objective, but it occupies a lower place in the American pantheon of noble objectives than the protection of our people from suspicionless law-enforcement searches."
The ruling means a person's DNA can be collected using a cheek swab even if he is wrongly arrested. Proponents say DNA will be taken only from those arrested for serious crimes, but the court ruling doesn't include that caveat.
Diluting the Fourth Amendment to such a degree should not be taken lightly. Already in post-9/11 America - as evidenced by this week's news of the Obama administration's mass collection of phone records - rights once taken for granted are treated as optional amid efforts to protect our vulnerabilities.
Americans have long accepted vulnerability as part of the price of liberty. But today many believe it's more important to feel safe.
The federal government and 28 states already take DNA from everyone arrested. The court could have stopped that injustice under the Fourth Amendment. Instead, it made an end run around the Constitution by declaring that DNA collection, like fingerprinting, is for identification.
That assessment, as Scalia put it, "taxes the credulity of the credulous." DNA will be used to match people to crimes they aren't even suspected of committing.
By this logic, police should be allowed to search your house for drugs if you are arrested in a bar fight. The court's decision fuels hyperbolic fears that this nation is becoming a police state.