Hunter Biden, the son of US President Joe Biden filed a complaint against Rudy Giuliani on Tuesday, accusing him of computer fraud for accessing personal information on his computer.
In a civil suit filed in California, Hunter Biden said Giuliani and Robert Costello, a lawyer for the former New York mayor, were responsible for the "total annihilation" of his digital privacy.
The 53-year-old Hunter Biden, who lives in California, is asking for a jury trial and unspecified damages.
In 2020, in a bid to embarrass Joe Biden ahead of the November presidential election, Giuliani and Trump's allies circulated data from a laptop that Hunter Biden allegedly abandoned at a computer repair shop in Delaware.
"Defendants have dedicated an extraordinary amount of time and energy toward looking for, hacking into, tampering with, manipulating, copying, disseminating, and generally obsessing over data that they were given that was taken or stolen from Plaintiff´s devices," the Hunter Biden complaint said.
Hunter Biden sued the owner of the computer repair shop earlier this year and the Internal Revenue Service for disclosing his tax history.
The California suit is the latest legal challenge facing Giuliani, who has been indicted in Georgia along with Trump and others for conspiring to overturn the 2020 presidential election results in the southern state.
A judge has also found Giuliani liable for defaming two Georgia election workers and he is being sued by a former assistant for sexual assault and harassment.
Hunter Biden, a recovering drug addict, is currently under investigation by a Justice Department special counsel for possible tax evasion and is to appear in court in Delaware next month on a firearms violation.
Hunter Biden´s business dealings in Ukraine and China while his father was vice president have been a constant target of Republicans and House Speaker Kevin McCarthy, bowing to pressure from the party´s hard right, authorised the launch of an impeachment investigation this month into Joe Biden.
Hunter Biden has not been charged with any crimes related to his foreign business dealings, however, and no credible evidence has emerged so far that the president was involved in anything illegal.