[1] Koštunica won the 2000 Yugoslav presidential election as a candidate of a broad alliance Democratic Opposition of Serbia (DOS), which led to overthrow of Slobodan Milošević and the withdrawal of international sanctions against Yugoslavia.

After the 2003 Serbian parliamentary election, the first elections after the dissolution of DOS and assassination of Prime Minister Zoran Đinđić, Koštunica formed a minority government with the support of Milošević's Socialist Party of Serbia and became the head of government.

[1] Koštunica was an assistant at the faculty from 1970 until 1974, when he left due to a political purge at the university for criticising the communist regime of Josip Broz Tito.

[1] Supported by both nationalists and liberals, the Democratic Opposition of Serbia backed him in the 2000 presidential election against incumbent Slobodan Milošević.

Milošević disputed the results of the first round, claiming that Koštunica had only received 49 percent of the vote and a runoff was required.

The Otpor movement, a student-led movement to oust Milošević and install free and fair elections, organized a protest where thousands of Serbians participated in strikes and took over the Belgrade capital and forced Milošević to accept the results and step down as president.

[10] Koštunica became prime minister in March 2004 at the head of the new minority government, albeit with the support of the Socialist Party of Serbia.

[12] Pro-EU candidate Boris Tadić and his Democratic Party wound up winning the parliamentary elections[13] and on July 7, a coalition between the Democrats and the Socialist Party was formed with Mirko Cvetković succeeding Koštunica as Prime Minister.

[14] Koštunica is a conservative politician with strong anti-communist views but also critical of the West, namely the United States and the European Union.

[15] In an interview with German weekly news magazine Der Spiegel, Koštunica stated he is "fairly close to de Gaulle", in his views.

There is no force, no threat, and no punishment big and hideous enough for any Serb, at any time, to say anything different but, Kosovo is Serbia!

and he asked "who in Serbia dares to ignore these facts and conceal the real goal of Solana's agreement.

[24] On 1 May 2008 Koštunica said that Russian Foreign Minister Sergey Lavrov was right when he said that the SAA should have been signed before Kosovo's unilateral declaration of independence and its recognition by 18 EU member states at the time.