Former New York City Mayor Bill de Blasio must pay a $475,000 fine levied against him for misusing public funds on a police security detail during his failed White House bid, a judge ruled this week, dismissing the ex-mayor’s legal challenge as “perplexing” and “entirely baseless.” The decision blocks de Blasio’s latest effort to erase the hefty fine issued against him by the city’s ethics board in 2023. In his motion for dismissal, de Blasio argued the board provided him with murky guidance around the use of public funds for security purposes, then overstepped its authority in imposing the fine. Judge Shahabuddeen Ally roundly rejected those arguments in an 80-page ruling issued Monday, finding the mayor was “expressly and specifically” informed that the city would not bear security travel costs for the cross-country campaign, but elected to bring his police detail anyway. “(His) position essentially eliminates his own agency in the choices he made,” the judge wrote, adding that there was no merit to “the remarkable contention that he is somehow not subject to the City’s conflicts-of-interest laws.” The ruling leaves de Blasio on the hook for a $320,000 in airfare and other travel costs incurred by his security detail during the four-month campaign, which he launched in 2019 while serving his second term as mayor. He will also have to pay a fine of $5,000 for each of the security detail’s 31 out-of-state trips, amounting to $155,000. The fine was the largest ever handed down by New York’s Conflicts of Interest Board, an independent city agency tasked with holding local officials to certain ethical standards. Carolyn Lisa Miller, the executive director of the board, said the judge's ruling “speaks for itself.” An attorney for de Blasio, Andrew G. Celli Jr., declined to comment. De Blasio did not return a text message. In the court filing, attorneys for de Blasio argued that forcing him to cover the cost of his security detail’s travel expenses violated his 1st Amendment rights, creating an “unequal burden” between wealthy candidates and career public servants. They added that paying the reimbursement would have “no appreciable effect on the budget of the NYPD.” De Blasio has faced previous allegations of misusing his security detail. Months before he left office in 2021, a report by the city’s Department of Investigation found he treated the officers as a “concierge service,” using them to move his daughter into an apartment and shuttle his son to college. Since leaving office in 2021, de Blasio has worked as a lecturer at multiple universities, most recently the University of Michigan, and delivered paid speeches in Italy.