A former deputy mayor of the city of Barcelona in north-eastern Spain, Forn served as Minister of the Interior from July 2017 to October 2017 when he was removed from office following the Catalan declaration of independence.

A supporter of Catalan independence, Forn joined the nationalist Democratic Convergence of Catalonia (CDC) whilst a student.

On 30 October 2017 charges of rebellion, sedition and misuse of public funds were brought against Forn and other members of the Catalan government.

[8][9] After being home schooled, he joined the Lycée Français de Barcelone aged 13, avoiding the Spanish francoist education.

[21][22] The Catalan Parliament passed legislation on 6 September 2017 authorising the referendum which would be binding and based on a simple majority without a minimum threshold.

[36][37] Almost immediately the Senate of Spain invoked article 155 of the constitution, dismissing Puigdemont and the Catalan government and imposing direct rule on Catalonia.

[38][39] The following day Spanish Prime Minister Mariano Rajoy dissolved the Catalan Parliament and called for fresh regional elections on 21 December 2017.

[40][41] On 30 October 2017 Spanish Attorney General José Manuel Maza laid charges of rebellion, sedition and misuse of public funds at the Audiencia Nacional against Puigdemont, Forn and other members of the Catalan government.

[47][48] Forn and Bassa flew back to Barcelona on 31 October 2017 where they were met at El Prat Airport by a group of Spanish nationalists hurling abuse and taunting the former ministers.

[51][52][53] On 2 November 2017 Audiencia Nacional judge Carmen Lamela remanded in custody Forn and seven other Catalan ministers (Bassa, Borrás, Oriol Junqueras, Carles Mundó, Raül Romeva, Josep Rull and Jordi Turull) as she considered them a flight risk.

[60][61] They were allegedly handcuffed behind their backs without seat belts in a van going very fast, forced to listen to the Spanish national anthem on a loop and threatened by their guards.

[61][62][63] Earlier, as the ministers arrived at the Audiencia Nacional, Spanish police officers were shown, in video obtained Reuters and published by the La Vanguardia, making sneering, homophobic comments about the ministers, with one officer saying "Wait till you see what they do to the little teddy bear", referring to Junqueras, "When they get him on all fours, they’ll fix his eye".

[68][69][70] On 4 December 2017 Llarena released, after 32 days in prison, six of the ministers (Bassa, Borrás, Mundó, Romeva, Rull and Turull) on bail of €100,000 but ordered that their passports be confiscated.

[73][74][75] In denying them bail, Llarena claimed that it remained to be seen if their pledge to abide by Spanish law was "truthful and real" and that there was a risk that they would commit the same crimes if released.

[79] A Christmas crib sent to Forn and Junqueras in prison was returned to its sender Antoni Bargalló smashed and with Viva España scrawled on the box.

[80][81] Cuixart, Forn and Sànchez appeared before Supreme Court judge Pablo Llarena on 11 January 2018 to secure release from prison.

Prime Minister Pedro Sánchez said that he pardoned them because it was the best decision for Spain and Catalonia, but did not overturn their bans from holding public office.