John Bosnitch volunteered to help 11th World Chess Champion Bobby Fischer (March 9, 1943 – January 17, 2008) after Fischer was detained in Japan in 2004. The U.S. Bush Administration had told Japanese authorities that it had "revoked" Fischer's passport to try to bring him to trial in the United States for playing in a World Chess Championship rematch in Yugoslavia in 1992 in alleged violation of U.S. presidential sanctions against economic activity with Yugoslavia.
Japanese immigration authorities then held Fischer in Tokyo's Narita Airport detention center for 16 days after refusing to let him leave the country due to an alleged passport violation, before transferring him to a long-term detention center pending deportation to the United States. Bosnitch set up the "Committee to Free Bobby Fischer" after visiting Fischer in the Narita Airport detention center. John Bosnitch argued for and won the right to participate as a friend of the court before the Immigration Bureau tribunal charged with handling Fischer's deportation. Bosnitch filibustered for more than 24 hours through two deportation hearings and then worked to legally block the Japanese Immigration Bureau's efforts to deport Fischer to the United States, coordinating a 9-month legal and public relations 'Free Bobby Fischer' campaign until Fischer's eventual release. Fischer was, after receiving full Icelandic citizenship, allowed to leave for Iceland, instead of being deported to the US.
Shortly before Fischer's departure for Iceland, on March 23, 2005, Bosnitch and Fischer appeared on the BBC World Service, via a voice link to Bosnitch's mobile telephone at the Tokyo airport. Bosnitch stated that Fischer would never play traditional chess again. Igor Stevanovic made a documentary film about chess legend Bobby Fischer through the eyes of his Serbian friends, chess opponents and acquaintances titled "Requiem for Bobby Fischer" (Opelo za Bobija Fisera, 2009) featuring John Bosnitch.
John Bosnitch also appears in the documentary "Me & Bobby Fischer" by Icelandic filmmaker Fridrik Gudmundsson, that focuses on the role played by a committee of Icelandic activists who joined the battle to save Bobby Fischer by fighting to gain sanctuary for him in Iceland.