Hunter left the laptop in Mac Isaac's Delaware shop for repairs in 2019 but never picked it up.
The next year, weeks before the election that pitted Joe Biden against incumbent Republican Donald Trump, the New York Post claimed it had emails and other documents from Hunter's laptop that implicated him and his father in questionable business dealings with Ukraine while Biden senior was vice president in 2015.
The Post said the shop owner handed the laptop over to the FBI and also made a copy of the hard drive and gave it to former New York mayor Rudy Giuliani, Trump's personal lawyer.
While President Biden has repeatedly dismissed the allegations, they have not gone away, and materials from the laptop figure in to the Republican-controlled House Oversight Committee's new probe into the business dealings of Hunter Biden and his family.
On Thursday the committee released documents that purportedly showed Hunter and some relatives benefitted from $3 million that a Chinese energy company paid a business associate, Rob Walker, in 2017.
Hunter Biden alleged in the lawsuit that Mac Isaac illegally accessed and took contents of his hard drive, and provided it to anti-Biden operatives like Giuliani.
"Mac Isaac readily admits that, however he came into possession of such material, his intrusion included viewing and accessing sensitive, private material," the suit said.
"The material he then provided to others included photos of Mr. Biden using drugs, without clothes, and involved in intimate relations with other adults," it said.
The suit came after Hunter Biden, now an artist, built a new legal team to push back against the House investigation against him, as his father prepares his decision on whether to run for reelection against year.