Tauran was created Cardinal-Deacon of Sant'Apollinare alle Terme by Pope John Paul II in the consistory of 21 October 2003. On the following 24 November, he was named Archivist and Librarian of the Holy Roman Church, overseeing the Vatican Secret Archives and Vatican Library. In late 2003, Tauran drew attention to the "second-class" treatment of non-Muslims in "many Muslim countries," especially Saudi Arabia. Representing the Pope, Tauran attended the March 2005 dedication of the new Holocaust museum at Yad Vashem in Jerusalem. Tauran was one of the cardinal electors who participated in the 2005 papal conclave that selected Pope Benedict XVI. He was also one of the cardinal electors in the 2013 conclave that elected Pope Francis. In the days prior to the 2013 conclave, the Vaticanologist John L. Allen, Jr. viewed Tauran as a "long-shot" papabile. "On paper," Allen remarked, "Tauran profiles as virtually the perfect anti-candidate, meaning someone who really shouldn't be in the running at all: a history of health scares, a career bureaucrat with zero pastoral experience, and a delicate personality at a time when many cardinals are seeking a strong governor." As the Cardinal Protodeacon at the 2013 conclave, he announced the election of the new pope on 13 March 2013 and bestowed the pallium on Pope Francis at his papal inauguration on 19 March. In his role as Protodeacon for the 2013 conclave Tauran said that "people asked 'How do you prepare yourself for the Habemus Papam?' I'd say 'No, I'm preparing myself for the conclave.' The conclave is not like the parliament with a campaign. It's a spiritual meeting. You have to remember the conclave is a liturgical celebration particularly from the morning to the evening. It's a spiritual experience. It was very deep for me. It's the manifestation of the singularity of the Catholic Church. You can feel the richness of the life of the church and how the positive aspects are greater than the negative ones". Cardinal Tauran exercised his option to be promoted to cardinal-priest and accordingly on 12 June 2014, Pope Francis elevated Tauran to the title of Cardinal-Priest. He was succeeded as Protodeacon by Cardinal Renato Raffaele Martino.
Pope Francis named Tauran to replace Cardinal Tarcisio Bertone as Camerlengo of the Holy Roman Church on 20 December 2014. Tauran was sworn in as Camerlengo, in the presence of Pope Francis, on 9 March 2015.
Death
Tauran showed evidence of Parkinson’s disease as early as 2003, but his condition had stabilized sufficiently by 2007 for him to take on the Pontifical Council presidency. Tauran died aged 75 on 5 July 2018 in Hartford, Connecticut, where he had been hospitalized for treatment of Parkinson's. His remains were transferred to Rome where he received the customary funeral rites of a cardinal of the Roman Curia.
Views
War in Iraq
Tauran was a "fierce critic" of U.S. plans to invade Iraq in 2003, which he said would constitute a "crime against peace" and a violation of international law. In August 2007 he said that the facts speak for themselves on Iraq, and that Christians had been better protected under Saddam Hussein.
Interfaith relations
Each year the Pontifical Council for Interreligious Dialogue sends a message, signed by its president, to Hindus for the festival of Diwali, which is celebrated during the month of October. In the 2017 message, Tauran called for the promotion of integral development, protection of human life and respect for the dignity and fundamental rights of the person. The Council sends similar messages each year on the occasion of the feasts of Eid ul-Fitr and Vesak.
Sharia
In a breakfast meeting with journalists, in March, 2008, Tauran said Rowan Williams, the Anglican Archbishop of Canterbury, had been "mistaken and naive" for suggesting that some aspects of Sharia law in Britain were unavoidable. He also lamented the fact that relations with Islam so dominated interreligious dialogue, and that all religions needed to be addressed on equal terms with none assigned second-class status.