To bring the judiciary into line with European Union legislation, the government had previously proposed changing the way judges and prosecutors are elected, and the National Assembly adopted it by a two-thirds majority on 7 June 2021, shortly before the parliamentary election in which the ruling Serbian Progressive Party (SNS) won a supermajority of seats.

The law, which was met with opposition from non-governmental organisations and activists, abolished the 50% turnout that was required for referendums to be considered valid.

In January 2020, state secretary Radomir Ilić called for the constitution to be changed to adopt "external control", which would give powers to the president of Serbia to appoint and remove judges.

[14][15][16] The law on referendum and people's initiative, which had been on the waiting list since the implementation of the 2006 constitution,[17] was adopted by the National Assembly on 11 November 2021.

[18] It was mainly criticised by non-governmental organisations and opposition politicians due to the abolishment of the 50% turnout for a referendum to pass, and the possibility of abusing the law on cases such as Rio Tinto.

[55] The question on the referendum paper was posed as "Are you in favor of confirming the act on changing the Constitution of the Republic of Serbia?"

(Serbian Cyrillic: Да ли сте за потврђивање акта о промени Устава Републике Србије?, romanized: Da li ste za potvrđivanje akta o promeni Ustava Republike Srbije).

[44] Analysts had concluded that the turnout and success of the referendum were equally important for the government, but that due to the April general elections, the campaign for the constitutional changes would be restrained.

[59] Additionally, Josep Borrell had called Kosovo to allow the collection of votes on its territory under the supervision of the Organization for Security and Co-operation in Europe.

[71][72][73] The incumbent justice minister Maja Popović, who participated in the talks and the formation of the final document,[74] was also supportive of such changes.

[90][91] The Democratic Party of Serbia and POKS also voiced their opposition to such changes,[92] and called for citizens to vote "no" on the referendum.

[93][94] Political activists Srđan Škoro, Đorđe Vukadinović, and Boris Malagurski also stated their support for the "no" option,[95] including several university professors.

[102] They had claimed that if the referendum passes, Rio Tinto would allegedly appoint their "team of judges" that would overturn any decision that is in their interest,[71] and that the judiciary would lose all of its power.

[103] Dveri and Serbian Radical Party officials also stated that citizens should vote "no",[104][105] and that "Serbia should not obey the demands of the European Union".

[137][138] Later that day, a group of activists from the "1 of 5 million" organisation were issued a warrant after they had tried to enter the building of Republic Electoral Commission.

[156][157][158] Protests which were organised by Dveri, Serbian Party Oathkeepers, Healthy Serbia, and POKS were held a day later after the referendum in front of the building of RIK.

[159] MP Vladan Glišić submitted an objection to RIK, in which he claimed that votes were falsified in 3,393 polling stations.

[163][164] Some had also stated that "the results of the referendum suits both the government and the opposition",[165][166] and that the "record low turnout raised the question of the legitimacy of constitutional changes".

[171][172][173] Prime minister Brnabić congratulated citizens and added that "for the first time in recent history, Serbia will get an independent judiciary".

[176][177] Olivér Várhelyi stated that "the voters in Serbia supported the change of the constitution to strengthen the independence of the judiciary".

[179] Miloš Jovanović and Pavle Grbović, presidents of the Democratic Party of Serbia and Movement of Free Citizens respectively, had stated that "SNS was defeated in the referendum" and had pointed out that "control of polling stations will be of key importance for the 3 April elections".

[181] Đorđe Vukadinović stated that "the level of turnout was expected due to low public interest" and that "it is a relative victory for citizens who have shown the strength that both the government and opposition must count on".

[182] Political scientist Cvijetin Milivojević [sr] stated that "the government nor the opposition won, but that the citizens lost instead".