NEW YORK - Mr Robert F. Kennedy Jr’s independent presidential campaign was dealt a blow on Aug 12 when a judge ruled that his petition to appear on New York’s ballot was invalid, saying he had used a “sham” address to maintain his New York residency.

       The ruling, if it stands, would kick Mr Kennedy off the ballot in a state where he lived for much of his adult life and could endanger his efforts to be placed on the ballot in dozens of other states. He has three days to appeal the decision, handed down by a judge in Albany, New York.

       A group of New York residents – backed by Clear Choice, a Democrat-aligned political action committee – had challenged Mr Kennedy’s New York residency, arguing that his campaign had used a false address on the tens of thousands of nominating petitions it circulated and submitted to place him on the ballot.

       His lawyer William F. Savino said in an email that Mr Kennedy had “always planned to appeal any adverse ruling”. Later on Aug 12, the campaign said it would file a lawsuit in federal court in Manhattan.

       “The 12th Amendment of the US Constitution governs the residency of presidential and vice-presidential candidates, not state law,” said the campaign’s senior counsel Paul Rossi. “If state court judges are going to ignore the Constitution, the federal courts must step in to protect voters’ rights.”

       For his part, Mr Kennedy said: “The Democrats are showing contempt for democracy. They aren’t confident they can win at the ballot box, so they are trying to stop voters from having a choice. We will appeal, and we will win.”

       Clear Choice said the ruling “makes clear that Mr Kennedy lied about his residency and provided a false address on his filing papers and candidate petitions in New York, intentionally misleading election officials and betraying voters’ trust”.

       The decision, by Justice Christina L. Ryba, a state Supreme Court judge, could open Mr Kennedy up to other challenges in states where he is on the ballot, because his campaign used the same address to gather signatures in those states.

       Ms Lis Smith, a strategist for the Democratic National Committee, which has backed some of the challenges to Mr Kennedy, said in a statement, “We’ll be assessing our options in other states based off of this ruling.”

       The Democratic Party has dedicated a substantial ground operation to challenging third-party candidate ballot access, which party leaders view as a threat to the Democratic ticket. For much of the past year, polling suggested that Mr Kennedy would pull voters about equally from former President Donald Trump and from President Joe Biden; more recent polls suggest that his appeal has diminished and that he draws more from Trump than from Vice-President Kamala Harris.

       As of Aug 9, Mr Kennedy was on the ballot in 19 states, including the crucial battlegrounds of Michigan and North Carolina, and the campaign has submitted petitions or filed for third-party status in more than 20 others, including New York.

       The campaign has won several other ballot challenges, in states including Hawaii, New Jersey and North Carolina.

       Mr Kennedy, 70, an environmental lawyer, spends most of his time at a home in Los Angeles that he shares with his wife, actress Cheryl Hines. But the petitions circulated this year in New York listed an address for him in Katonah, a hamlet about 45 miles north of New York City in Westchester County.

       For decades before he moved to Los Angeles, in 2014, he lived in New York, where he raised a family and long fought for cleaning up the Hudson with the group Riverkeeper.

       Lawyers for the voters who were seeking to invalidate his ballot access petition say that the Katonah address belonged to a friend and that he never lived there.

       The trial began on Aug 5. Mr Kennedy’s lawyers did not give an opening statement, but in a statement posted on the campaign’s website they said he received mail in Katonah and had driver’s, fishing and falconry licenses from New York.

       “New York has been his residence continuously since 1964, and Mr Kennedy has deep ties to it,” Savino said in the statement. “He intends to move back to New York as soon as his wife retires from acting.”

       During the four-day hearing, the lawyers for the four voters who brought the suit called Ms Barbara Moss, who owns the house in Katonah. She said Mr Kennedy stayed in a spare bedroom.

       The bedroom was referred to in the judge’s ruling on Aug 12: “The court finds Kennedy’s testimony that he may return to that bedroom to reside with his wife, family members, multiple pets and all of his personal belongings to be highly improbable, if not preposterous.”

       She concluded that Mr Kennedy had demonstrated a “longstanding pattern of borrowing addresses” to keep up the appearances of New York residency.

       The Katonah home, the judge said, was “merely a ‘sham’ address that he assumed for the purpose of maintaining his voter registration and furthering his own political aspirations in this state.” NYTIMES