The Supreme Court on Monday empowered police to stop people on the streets and question them, even when it is not clear they have done anything wrong.

In a 5-3 ruling, the Supreme Court relaxed the so-called exclusionary rule and upheld the use of drug evidence found on a Utah man who was stopped illegally by an officer in Salt Lake City.

The Supreme Court, in an opinion by Justice Clarence Thomas, said that because the Salt Lake City man had an outstanding arrest warrant for a traffic violation, the illegality of the stop could be ignored.

“In this case, the warrant was valid, it predated [the police officer's] investigation, and it was entirely unconnected with the stop,” Thomas wrote for the majority.

The issue of illegal stops was raised last month in the trial of Edward Nero, one of six Baltimore officers charged in the arrest and death of Freddie Gray.

The 25-year-old Gray died last year of injuries sustained while riding in the back of a police transport van. Prosecutors argued that Nero committed an assault by detaining Gray without justification. But Nero's attorneys had argued that countless court decisions backed the officers' actions, saying officers may chase a suspect in a “high-crime” area and detain him while seeking to confirm or dispel their suspicions.

Nero was acquitted on all counts by Circuit Judge Barry G. Williams.

Legal experts have said that when the constitutionality of a police stop is questioned, the typical remedy is for charges to be dropped or evidence suppressed.

The Supreme Court decision, however, would uphold such evidence if an outstanding warrant is discovered.

“By weakening that rule, we're weakening one more restraint that encourages the police to respect the constitutional rights of Baltimore citizens,” said David Jaros, a University of Baltimore law professor.

Jaros said the ruling could embolden officers to casually stop and search people despite protections under the Fourth Amendment.

Doug Colbert, a University of Maryland law professor, added: “You're basically encouraging police to stop whomever they want for the purpose of: ‘I want to see if you have any open warrants. And once I find that you have an open warrant for not paying a parking ticket, now I can look into your pockets.'?”

Colbert said such searches would primarily fall on poor and minority families. There are about 40,000 outstanding warrants against adults in Baltimore, he said, mostly for failing to pay fines and missing court dates.

“It's a way of making an entire population vulnerable to arrest,” Colbert said.

The high court's three female justices dissented and warned that the ruling will encourage police to randomly stop and question people because they face no penalty for violating citizens' rights. They also said racial minorities in major cities will be most affected.

“The court today holds that the discovery of a warrant for an unpaid parking ticket will forgive a police officer's violation of your 4th Amendment rights,” Justice Sonia Sotomayor wrote in dissent.

Thomas, rebutting the dissenters, said the case did not involve a “flagrant violation” of the Fourth Amendment. He said he doubted “police will engage in dragnet searches if the exclusionary rule is not applied. We think this outcome is unlikely.”

The Supreme Court first adopted the exclusionary rule for federal cases in 1914, but greatly expanded its reach in 1961 by applying the rule to state and local police. The rule generally requires judges to throw out evidence if a police officer or federal agent conducted an unreasonable search, including stopping a pedestrian without reasonable suspicion that the person had committed a crime.

The Fraternal Order of Police Lodge 3, which represents rank-and-file officers in Baltimore, did not respond to a request for comment on the Supreme Court decision. But Tod Burke, a former Maryland police officer and criminal justice professor at Radford University, said he doesn't believe the decision will encourage “fishing expeditions” by officers.

The Utah case began when a Salt Lake City police officer saw a man walking away from a house where drug dealing was suspected. He stopped Edward Strieff in the parking lot of a nearby convenience store and asked to see his identification.

When Detective Douglas Fackrell relayed the information to a police dispatcher, he was told Strieff had an outstanding warrant for a “traffic violation.” Based on that, he arrested Strieff, searched him and found a bag of methamphetamine.

Strieff was charged with possession of an illegal drug, although the prosecutors conceded the officer had lacked “reasonable suspicion” when he stopped and questioned the man outside the convenience store.

The Utah Supreme Court reversed Strieff's drug conviction on the grounds that the illegality of the stop required prosecutors to throw out the evidence against him. The Supreme Court agreed to hear the state's appeal and upheld the conviction Monday in Utah v. Strieff.

Baltimore Sun reporter Tim Prudente and the Tribune Washington bureau contributed to this article.