Huge questions over the privacy of Americans loom after the Supreme Court ruled this week that DNA from people arrested but not convicted could be collected. Several states already use the tactic and attribute it to solving crimes.

On Monday, the Supreme Court’s 5-4 decision upheld the DNA collection of arrestees in the Maryland v. King case.

“DNA identification of arrestees is a reasonable search that can be considered part of a routine booking procedure,” Justice Anthony Kennedy said. “Taking and analyzing a cheek swab of the arrestee’s DNA is like fingerprinting and photographing, a legitimate police booking procedure that is reasonable under the Fourth Amendment.”

The case stems from Maryland’s DNA collection practices, which only apply to people arrested for “serious crimes like murder, rape, assault, burglary and other crimes of violence.”

In Maryland, Alonzo King’s DNA was taken after he pointed a gun at a group of people. It was later found that his DNA matched the perpetrator of an unsolved rape case. He was later convicted and received a life sentence.

Three liberal justices, Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan, and conservative Associate Justice Antonin Scalia said they feared that collecting DNA would be misused.

“Because of today’s decision, your DNA can be taken and entered into a national database if you are ever arrested, rightly or wrongly, and for whatever reason,” the justices said.

Opposition against the use of DNA came loud and clear as soon as the decision was handed down. In a statement from Steven R. Shapiro, legal director of the ACLU, he said it creates a new exception for the Fourth Amendment.

“While no one disputes the importance of that interest, the Fourth Amendment has long been understood to mean that the police cannot search for evidence of a crime–and all nine justices agreed that DNA testing is a search–without individualized suspicion,” Shapiro said. “Today’s decision eliminates that crucial safeguard.”

Shapiro added that other state laws on DNA testing are even broader than Maryland’s and may present issues that were not resolved by the ruling. Critics of the ruling believe that Blacks and poor people will be affected the most. In a column this week, legal expert and civil rights attorney Eric L. Welch Guster said that DNA collected whether suspects are guilty or not is a violation of human rights.

“As a Black man, this is horrifying because it will surely cause more unlawful stops, illegal arrests and unfair treatment of Blacks and the poor,” he said. “Although every police department will not be unfair, there will be those that will seize the opportunity.”