The U.S. Supreme Court has ruled in favor of police officers in two cases involving qualified immunity, the controversial legal doctrine that protects police officers accused of misconduct.

The two cases concerned police officers accused of using excessive force when responding to domestic disturbances. In one, officers used beanbag rounds and a knee on the suspect's back to subdue him; in the second, officers shot and killed the suspect after he approached them while raising a hammer.

Both decisions the court issued Monday were unsigned. No justices dissented.

Qualified immunity refers to a series of legal precedents that protect government officials — including police officers — accused of violating constitutional rights.

To win a civil suit against a police officer, complainants must show that the officer violated "clearly established law," most often by pointing to factually similar previous cases. Otherwise, officers are protected from liability.

Police advocates say that qualified immunity is necessary so that police officers can do their often-dangerous jobs without fear of frivolous lawsuits.

But those in favor of criminal justice reform say the doctrine has essentially created a Catch-22. Officers are shielded from liability even when it appears they violated civil rights because there is no "previously established law" to challenge them because similar cases have not been pursued because officers are shielded from such cases.

In practice, the doctrine has shielded officers from liability in hundreds of civil cases, even when accused of destroying property, killing innocent people they mistook for suspects or stealing thousands of dollars.

The cases involved police officers accused of excessive use of force

The first of Monday's two cases concerned Daniel Rivas-Villegas, a police officer in Union City, Calif., who responded to a 911 call from a 12-year-old girl who, along with her mother and 15-year-old sister, had barricaded herself inside a room to hide from her mother's boyfriend, Ramon Cortesluna, who was reportedly using a chainsaw to destroy things in the house.

When officers arrived and confronted Cortesluna, they discovered he was carrying a knife. Another officer fired two nonlethal beanbag rounds at Cortesluna, after which he followed police orders to lie down. Rivas-Villegas knelt on Cortesluna's back and held up his arms as another officer retrieved the knife. After the incident, Cortesluna sued over use of excessive force.

The 9th Circuit Court of Appeals found that Rivas-Villegas was not entitled to qualified immunity, citing similarities to a previous case called LaLonde vs. the County of Riverside, in which two police officers were denied qualified immunity after kneeling on a facedown unresisting suspect named John LaLonde.

But in reversing the appeals court's decision, the Supreme Court cited several factors set the two incidents apart: The officers in LaLonde were responding to a noise complaint, not a domestic violence emergency; LaLonde was unarmed, while Cortesluna was carrying a knife; and Rivas-Villegas had knelt on Cortesluna for only eight seconds as officers retrieved the knife.

In the second case, three police officers in Tahlequah, Okla., responded to an emergency call from a woman whose ex-husband, Dominic Rollice, was drunk and refusing to leave her home.

The officers confronted Rollice in the garage, where he grabbed a hammer. The officers drew their guns and yelled for Rollice to drop it. Instead, Rollice moved toward them and raised the hammer higher; two officers shot and killed him.

A lower court found that the Tahlequah officers had violated Rollice's Fourth Amendment rights when they "recklessly created the situation that led to the fatal shooting."

The Supreme Court reversed the court's decision, saying "not one" of the cases cited by the lower court "comes close to establishing that the officers' conduct was unlawful."

The doctrine has critics, but so far, efforts to change it have not succeeded

Justices Sonia Sotomayor and Clarence Thomas — among the court's most liberal and most conservative members, respectively — have previously criticized qualified immunity, though neither issued a dissent Monday.

Congressional Democrats have made multiple attempts in recent years to limit qualified immunity, though none has been successful. The George Floyd Justice In Policing Act, which passed the House, would have restricted the defense, but negotiations over a compromise bill petered out earlier this year.

"By shielding police officers from accountability, qualified immunity encourages more police violence against Black and Brown people," said Sen. Ed Markey of Massachusetts, a co-sponsor of a standalone Senate bill that would end qualified immunity, on Twitter after Monday's ruling.

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