Harvard students Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra accused Zuckerberg of intentionally making them believe he would help them build a social network called HarvardConnection.com (later called ConnectU). They filed a lawsuit in 2004; it was dismissed on a technicality on March 28, 2007. It was refiled soon thereafter in federal court in Boston. Facebook countersued in regards to Social Butterfly, a project put out by The Winklevoss Chang Group, an alleged partnership between ConnectU and i2hub. On June 25, 2008, the case settled and Facebook agreed to transfer over 1.2 million common shares and pay $20 million in cash.
In November 2007, confidential court documents were posted on the website of 02138, a magazine that catered to Harvard alumni. They included Zuckerberg's Social Security number, his parents' home address, and his girlfriend's address. Facebook filed to have the documents removed; the judge ruled in favor of 02138.
A lawsuit filed by Eduardo Saverin against Facebook and Zuckerberg was settled out of court. Though terms of the settlement were sealed, the company affirmed Saverin's title as co-founder of Facebook. Saverin signed a non-disclosure contract after the settlement.
Pakistan criminal investigation
In June 2010, Pakistani Deputy Attorney General Muhammad Azhar Sidiqque launched a criminal investigation into Zuckerberg and Facebook co-founders Dustin Moskovitz and Chris Hughes after a "Draw Muhammad" contest was hosted on Facebook. The investigation named the anonymous German woman who created the contest. Sidiqque asked the country's police to contact Interpol to have Zuckerberg and the three others arrested for blasphemy. On May 19, 2010, Facebook's website was temporarily blocked in Pakistan until Facebook removed the contest from its website at the end of May. Sidiqque also asked its UN representative to raise the issue with the United Nations General Assembly.
Main article: Paul Ceglia
In June 2010, Paul Ceglia, the owner of a wood pellet fuel company in Allegany County, upstate New York, filed suit against Zuckerberg, claiming 84 percent ownership of Facebook and seeking monetary damages. According to Ceglia, he and Zuckerberg signed a contract on April 28, 2003, that an initial fee of $1,000 entitled Ceglia to 50% of the website's revenue, as well as an additional 1% interest in the business per day after January 1, 2004, until website completion. Zuckerberg was developing other projects at the time, among which was Facemash, the predecessor of Facebook, but did not register the domain name thefacebook.com until January 1, 2004. Facebook management dismissed the lawsuit as "completely frivolous". Facebook spokesman Barry Schnitt told a reporter that Ceglia's counsel had unsuccessfully sought an out-of-court settlement.
On October 26, 2012, federal authorities arrested Ceglia, charging him with mail and wire fraud and of "tampering with, destroying and fabricating evidence in a scheme to defraud the Facebook founder of billions of dollars." Ceglia is accused of fabricating emails to make it appear that he and Zuckerberg discussed details about an early version of Facebook, although after examining their emails, investigators found there was no mention of Facebook in them. Some law firms withdrew from the case before it was initiated and others after Ceglia's arrest.
Hawaiian land ownership
In January 2017, Zuckerberg filed eight "quiet title and partition" lawsuits against hundreds of native Hawaiians to purchase small tracts of land which they own. This land is contained within the 700 acres of land in the Hawaiian island of Kauai that Zuckerberg had purchased in 2014. When he learned that Hawaiian land ownership law differs from that of the other 49 states, he dropped the lawsuits.
Testimony before U.S. Congress
On April 10 and 11, 2018, Zuckerberg began testifying before the United States Senate Committee on Commerce, Science, and Transportation regarding the usage of personal data by Facebook in relation to the Facebook–Cambridge Analytica data breach. He has called the whole affair a breach of trust between Aleksandr Kogan, Cambridge Analytica, and Facebook. Zuckerberg has refused requests to appear to give evidence on the matter to a Parliamentary committee in the United Kingdom
On October 1, 2020, the US Senate Commerce Committee unanimously voted to issue subpoenas to the CEOs of three top tech firms, including Zuckerberg, Google’s Sundar Pichai and Twitter’s Jack Dorsey. The subpoenas aimed to force the CEOs to testify about the legal immunity the law affords tech platforms under Section 230 of the Communications Act of 1934. US Republican argued that the law unduly protected social media companies against allegations of anti-conservative censorship.
In March 2021, it was announced that Zuckerberg would testify before Congress again on March 26, when he will be questioned about the role that Facebook played in the January 6, 2021 attack on the US Capitol Building.
Zuckerberg co-founded and is a board member of the solar sail spacecraft development project Breakthrough Starshot.