If police show up at the front door of a house occupied by two people and request permission to search the house, what happens if one occupant says no and the other says yes?

Seven years ago, the US Supreme Court answered that question, ruling that in the event of a tie between disagreeing occupants the objecting occupant wins. There would be no consent for a police search.

On Wednesday, the high court took up a similar case, but with an important twist. What happens if one occupant objects to a search, the police then arrest the objecting occupant, and subsequently obtain consent to search from the other occupant?

That’s the question in Fernandez v. California (12-7822), a case involving a police search of an apartment in Los Angeles shared by a suspected street gang member and his girlfriend.

The case is important because it will help define the contours of the Fourth Amendment protection against unreasonable searches and seizures by the police.

More specifically, it will help give clear notice to the police and to judges what the rules are when police seek permission to conduct a warrantless search of a residence.

Under the Fourth Amendment, law enforcement officials are required to obtain a judicially-authorized warrant before conducting a search of a home. But there is nothing stopping police from simply asking an occupant for permission to search.

If permission is given, no warrant is necessary and any evidence or illegal contraband discovered can be seized and used in a trial.

The high court case stems from a series of events in October 2009 involving Walter Fernandez, a suspected member of the Drifters, a criminal street gang.

The events began with an armed robbery by someone with a gang-related tattoo on his head who matched Mr. Fernandez’s description. Shortly after the robbery, two police officers were positioned near Fernandez’s apartment building, a known hangout of the Drifters.

The officers saw a man run into an apartment. Moments later they heard yelling and the sounds of a fight. After calling for backup, five police officers approached the apartment.

A woman, Roxanne Rojas, answered the door, holding a two-month-old baby. Ms. Rojas’s face was freshly bruised and it appeared she’d been bleeding.

As the police asked Rojas to step outside, Mr. Fernandez appeared in the kitchen wearing only boxer shorts. He was sweating. “You don’t have any right to come in here,” he told the police. “I know my rights.”

The officers entered the home, placed Fernandez under arrest for suspected domestic violence against Rojas, and took him downstairs and away from his girlfriend.

As they were leading Fernandez downstairs, one of the officers noticed the tattoo on the suspect’s head and that it matched the description from the recent robbery. The robbery victim was brought to the apartment building where he identified Fernandez as the person who robbed him.

Roughly an hour after Fernandez was led downstairs, the lead police officer returned to the apartment. He asked Rojas for her consent to search the apartment. According to briefs in the case, Rojas did not want to consent to the search, but she did so anyway.

Police found a sawed-off shotgun, ammunition, and a knife. They also found clothing matching the description given from the robbery scene.

Fernandez was charged with three different crimes, unlawful possession of firearms, domestic violence, and robbery.

Before the trial, his lawyer sought to suppress the evidence seized during the search of the apartment. He argued that the police did not obtain valid consent to conduct the search. They either needed consent from both Rojas and Fernandez or they needed a warrant, he said.

The trial court rejected the argument. Fernandez then pleaded no contest to the gun charges, pending the outcome of his appeal.

In the meantime, he was convicted of the two other charges and sentenced to 14 years in prison.

At issue before the high court is whether Rojas’s consent was enough to justify the police search, or whether the search was improper because Fernandez had clearly stated his objection to a search when police first arrived.

The justices appear to be sharply split on the issue. Several expressed concern Wednesday that if they established a hard and fast rule that the objection of a co-tenant could not be overturned by the other, it might leave women who are domestic violence victims in a precarious position.

“It’s her house, too,” Justice Stephen Breyer said. “Can’t she invite people into her house, too, whom she wants, including the policeman?”

Jeffrey Fisher, a Stanford Law School professor representing Fernandez, said a domestic violence victim could retrieve a dangerous or illegal item from the house and give it to police at the front door. He added that if there was probable cause to suspect a crime, police could secure the house long enough to obtain a search warrant.

Justice Anthony Kennedy expressed skepticism about Professor Fisher’s position. He said if the court endorsed a rule that would allow a co-tenant’s objection to stand long after the co-tenant had been charged and removed from the scene it would mark a “vast expansion” of the court’s prior legal precedent.

Fisher said the Fernandez case was a rare instance, and that in most cases police would obtain valid consent. He said if the high court upholds the search of Fernandez’s apartment it would give police complete control to conduct warrantless searches by simply removing an objecting occupant whenever the other occupant would allow a search.

Justice Ruth Bader Ginsburg asked why police did not obtain a warrant.

Chief Justice John Roberts suggested that police might have been concerned that other gang members would show up and attempt to retrieve any known contraband in the apartment.

Assistant US Solicitor General Joseph Palmore urged the justices to uphold the warrantless search based on the girlfriend’s consent.

In the high court’s 2006 case, he said, the justices ruled that if one of two co-occupants refuses to consent to a police search – when both co-occupants are present at the house – the police must abide by the wishes of the objector.

In contrast, he said, both co-occupants were not present at the time police obtained the agreement of Rojas to allow the search.

“When the objector is absent, there is no tie, and the normal rule applies,” Mr. Palmore said. “The normal rule is that each occupant has the authority in her own right to admit visitors to her own home.”

Justice Sonia Sotomayor asked why police felt a need to search the apartment. Rojas’s statement to police did not include any detail that would suggest there might be illegal items or contraband in the house, she said.

“I think this was just a pure – ‘We want to find something else,’ ” she said.

Palmore said the police officers were in the gang unit and were aware of a possible connection between Fernandez and the earlier robbery.

“They at that point had probable cause to get a warrant,” he said. But he added that they were justified in seeking Rojas’s consent to speed the investigative process.

A decision in the case is expected by next June.