Just before midnight on July 24, 2017, shots rang out at a mobile home park in Southaven, Miss. Police had come looking for a domestic violence suspect, only to knock on the door of the wrong house and then open fire on the innocent man inside. By the time paramedics arrived, 41-year-old Ismael Lopez, an auto mechanic known for mentoring troubled teens and fixing his neighbors’ cars for free, had died of a gunshot wound to the back of his head.

Now, attorneys for the city of Southaven are using an unusual approach to try to persuade a federal judge to dismiss the $20 million civil rights lawsuit filed by Lopez’s widow. They argue that because the victim was an undocumented immigrant, he wasn’t protected by the U.S. Constitution.

“We’re stunned that someone put this in writing,” Murray Wells, an attorney representing Lopez’s estate, told reporters at a Thursday news conference.

The U.S. Supreme Court has repeatedly ruled that people present in the United States have certain basic rights, regardless of their immigration status, affirming in two frequently cited rulings that undocumented immigrants can’t be denied an education or due process in a court of law.

But attorneys for the small city near Memphis claim that because Lopez had no “legally recognized relationship” with the United States, he had no rights under the Fourth Amendment, which protects against unreasonable searches and seizures, or the 14th Amendment, which guarantees equal protection to all citizens.

“If he ever had Fourth Amendment or Fourteenth Amendment civil rights, they were lost by his own conduct and misconduct,” attorney Katherine S. Kerby wrote in a brief filed Sept. 4. “Ismael Lopez may have been a person on American soil but he was not one of the ‘We, the People of the United States’ entitled to the civil rights invoked in this lawsuit."

At Thursday’s news conference, attorneys representing Lopez’s family called the strategy “chilling,” “ludicrous” and “insane.” The city’s argument, Wells said, amounted to telling undocumented immigrants that “stormtroopers can come into your house and kill you” without any repercussions.

The battle over legal standing is only the latest controversy surrounding Lopez’s death, which sparked protests in the northern Mississippi community and angered many Latino residents.

As The Washington Post’s Radley Balko previously wrote in an analysis of the case, police have claimed that Lopez cracked open the door to his house and pointed a gun at them, which his attorneys and his wife say is untrue. It’s also unclear whether the mechanic knew that the men who showed up unexpectedly at his home were police officers: DeSoto County District Attorney John Champion has said that he doesn’t believe the officers announced themselves before opening fire on Lopez and his pit bull after the dog ran out of the mobile home.

In July 2018, a grand jury declined to indict the officers involved in the fatal shooting, an outcome that outraged Lopez’s friends and family. Last June, Claudia Linares, Lopez’s widow, filed a lawsuit in the U.S. District Court for the Northern District of Mississippi.

In court filings, attorneys for the city have argued Linares lacks the standing to sue because she, too, is an undocumented immigrant. They also claim that she was not legally married to Lopez, while simultaneously accusing her of being married to two men at the same time and referring to her as a “bigamous paramour.” Linares’s legal team says that those charges are both false and extremely offensive, and last week filed a marriage certificate showing that the two were married in Arkansas in 2003.

“It’s a real shame that they have to use these tactics to soil someone’s name when she lost her partner, the love of her life, in a tragic accident,” attorney Aaron Neglia said at Thursday’s news conference.

In a statement shared with local media outlets, Southaven Mayor Darren Musselwhite replied that the city “will defend this matter in the court of law, not in the media via press conferences with ridiculously-misleading sound bites."

Kerby, the city’s attorney, has argued that there’s a legal precedent for saying that undocumented immigrants lack certain constitutional rights. In a Thursday interview with the Memphis Commercial Appeal, she pointed to a 1990 Supreme Court case, United States v. Verdugo-Urquidez, where justices ruled that the Fourth Amendment does not protect foreigners against unreasonable search and seizure when they are in foreign territory or international waters, even if their trial takes place in American courts.

In their filings, the attorneys representing Lopez’s estate counter that the ruling is irrelevant because it deals with a search that took place in Mexico. Lopez and his wife, although Mexican citizens, were on U.S. soil when police officers showed up at their house and opened fire. Wells told reporters on Thursday that Southaven’s attorneys “want to say it’s sort of like they were actually in Mexico when this happened.”

“But that’s not what happened,” he added. “They were in their home.”

Kerby also told the Commercial Appeal that she had based her argument on a 2011 case, United States v. Portillo-Munoz, where the Fifth Circuit Court of Appeals ruled against a Mexican man who claimed that federal statutes barring people who enter the country illegally from owning guns ran contrary to the Second Amendment. But Lopez’s team pointed out that the same ruling also made clear that the decision didn’t have any bearing on Fourth Amendment protections against government overreach.

At Thursday’s news conference, Wells said that he asked the judge presiding over the case to consider sanctioning the city for arguments that weren’t being made in good faith and for questioning the integrity of Lopez’s marriage.

“This case should have never been here in the first place,” he said. “It was an accident. They should have taken responsibility for it, and we should move forward.”

A reporter asked Linares for her thoughts.

“There are no words,” she replied in Spanish.