Days after writing an opinion piece for The San Diego Union-Tribune that urged city officials to sue the National Football League and the Chargers over the team’s move to Los Angeles, former City Attorney Michael Aguirre said he will take up the fight if Mayor Todd Gloria fails to act.Aguirre, who was the elected city attorney from 2004 to 2008, advised the mayor in a letter Friday that he would proceed with a lawsuit of his own next Friday if the city does not pursue its own legal complaint. “There is established legal precedent for the city of San Diego to recover taxpayer losses from the NFL and the Chargers, as was done under similar circumstances by the city of St. Louis and the St. Louis Regional Convention and Sports Complex Authority,” Aguirre wrote.“We write to confirm that you, as mayor of the city of San Diego, have decided not to take any legal action to recover damages the city suffered as a result of the Chargers relocation to Los Angeles starting in the 2017 football season,” he added.The Chargers played in San Diego for more than 50 years before moving to Los Angeles in 2017. The move came after years of community debate over a new stadium and a spate of proposals to keep them here. The Mayor’s Office did not immediately respond to a request for comment about Aguirre’s letter. But in an email last month to a person who asked Gloria about the possibility of suing the NFL, the mayor said it was too late to proceed with a lawsuit.“Unfortunately, previous administrations in the city of San Diego twice waived the city’s rights to any claim against the NFL and the Chargers for relocation after the 2008 NFL season,” Gloria responded to the man.“The attached 2004 and 2006 lease amendments contain this information,” the mayor added in his email. “Thank you again for your email and for staying engaged on this important issue.”Debate over a possible lawsuit against the NFL and the longtime San Diego home team resurfaced in December, after the city of St. Louis won a $790 million settlement over a claim filed in the wake of the Rams’ move to Los Angeles. Aguirre, who has been in contact with the Missouri attorney who put forward that legal argument, said the same litigation strategy could be employed in San Diego.“The NFL approved the Chargers’ move to Los Angeles at the same time it approved the Rams’ move there,” the one-term city attorney wrote in his opinion piece last week. “What the NFL did to St. Louis, it did even worse to San Diego.”According to Aguirre, the St. Louis lawsuit focused on the league’s violation of its own policy when it approved the relocation of both the Rams and the Chargers.Under the relocation policy, the league supports stable relations between teams and the communities in which they play, and clubs are obliged to work diligently and in good faith to maintain suitable stadium facilities, Aguirre said.The city of San Diego signed several deals to upgrade what was called Qualcomm Stadium, the publicly-owned facility that served as the Chargers’ home field since it was first built in the late 1960s, Aguirre said.But the Chargers nonetheless planned to leave San Diego as early as 2006, according to a former league employee quoted in an article last month by Union-Tribune columnist Bryce Miller.“I think (Chargers owner) Dean Spanos made up his mind to move in 2006,” former NFL official Jim Steeg told Miller. “It just took him 10 years to do it.” The same column quoted a former senior city lawyer who said the city bargained away its right to sue years ago, when San Diego and team officials each wanted to do away with an unpopular contract clause that had the city paying for unsold seats.“The goal was to ensure the Chargers stayed for a time and get rid of the ticket guarantee,” former Assistant City Attorney Les Girard told Miller. “I’m not sure it would be fair to say we could get something done (with the Chargers staying) but at least we had the opportunity.” Aguirre said the Chargers were profitable even without the benefit of a new stadium. The value of the team skyrocketed from the $40 million Spanos paid in 1984 to more than $1 billion before he moved the club to Los Angeles.In 2018, Aguirre and law partner Maria Severson won a $775 million settlement for consumers after suing Southern California Edison over a deal to charge ratepayers $5 billion for the failed San Onofre nuclear plant.