A court suspended Rudy Giuliani's law licence in the state of New York on Thursday for claiming that Donald Trump lost last year's presidential election because of fraud.
A New York court ruled that Mr Giuliani made "demonstrably false and misleading statements" as Mr Trump's lawyer during the ex-president's attempt to overturn his defeat to Joe Biden.
Mr Giuliani, 77, helped the Trump campaign file numerous lawsuits in several states alleging without evidence that the Democratic Party had rigged the election.
"These false statements were made to improperly bolster respondent's narrative that due to widespread voter fraud, victory in the 2020 United States presidential election was stolen from his client," the appellate court wrote in a 33-page ruling.
The court added that Mr Giuliani's conduct "immediately threatens the public interest and warrants interim suspension from the practice of law."
The request to remove his licence was filed by dozens of prominent lawyers who said they were acting to defend American democracy.
Mr Giuliani can challenge the decision, however the ruling noted that at the end of the proceedings he will likely face "substantial permanent sanctions."
The suspension is remarkable for the fact Mr Giuliani once served as the US Attorney for the Southern District of New York, one of the top prosecutor jobs in the United States.
Rudy Giuliani speaks during a news conference on legal challenges to vote counting in Pennsylvania on 4 November 2020, Source: AAP
He was also mayor of New York City for eight years, earning national acclaim for leading the US financial capital in the aftermath of the September 11, 2001 attacks on the US by Al-Qaeda.
Mr Giuliani is currently in the crosshairs of Manhattan prosecutors who are investigating his activities in Ukraine.
Mr Giuliani was Mr Trump's personal lawyer when the president was impeached in December 2019 for seeking political help from Ukraine.
FBI agents raided his New York home and offices in late April. He has denounced the operation as politically motivated.
In a statement Thursday, Mr Trump called Mr Giuliani a "great American patriot" and said the suspension was "nothing but a Witch Hunt."
