Puzyna was born in 1842 in what was then a part of the Austrian Empire and former part of the Kingdom of Poland, in the diocese of Lwów. He earned a doctorate in law from the University of Lwów on 24 June 1870. He began a career in civil administration, but decided to embrace an ecclesiastical career. Ordained a priest on 1 December 1878, he was a vicar at Przeworsk, and then became a Canon of the Cathedral of Przemyśl. He was named auxiliary bishop of the Latin-rite Archbishop of Lwów and titular bishop of Memphis on 26 February 1886. He was consecrated a bishop on 25 March of that same year by Mieczysław Halka-Ledóchowski, with Archbishop Franziskus von Paula Graf von Schönborn of Prague and Archbishop Joseph Sembratovych of Ukrainian rite Lwów. He was translated to the Archdiocese of Kraków on 22 January 1895. On 15 April 1901, Puzyna was created a cardinal-priest, with the title of Santi Vitale, Valeria, Gervasio e Protasio by Pope Leo XIII. He received his red hat on 9 June 1902. During the conclave of 1903, acting on behalf of his Sovereign, Emperor Franz Joseph I of Austria, he presented a veto against the election of CardinalMariano Rampolla. Puzyna wanted to avoid the election of Rampolla, who was sympathetic to Russia and Germany. Among other things, Rampolla sought to curry favor with Russia by abolishing the Polish language and instituting Russian in the Russian partition's Catholic churches. These were ethnic and linguistic considerations. Emperor Franz Joseph I of Austria, too, did not wish to see Rampolla elected to the Chair of Peter. He held a grudge against Rampolla for opposing a proper burial for his son Rudolf, Crown Prince of Austria, upon Rudolf's suicide. Rampolla also openly supported political forces in Austria that were hostile to the Emperor. The Emperor therefore authorized the Cardinal to present the veto in his name. On his way to the conclave, Puzyna met in Vienna with the Emperor and proposed that the Emperor present his veto, jus exclusivae, against Cardinal Rampolla. The Emperor subscribed to the idea, and Puzyna presented the veto on the third day of the conclave, in the name of His Apostolic Majesty Francis Joseph, Emperor of Austria and King of Hungary. When the veto was read, Cardinal Luigi Oreglia di Santo Stefano, the Dean of the College of Cardinals, replied, "This communication cannot be received officially or unofficially. No cardinal is to give any consideration to this 'veto' and all are to continue to vote according to their conscience." In other words, the attempt at a veto was rejected. It was the last time such a veto was used. The veto, although not recognized by canon law, and as such non-binding, still carried much political weight, as the cardinals feared opposing the manifest will of one of the Christian monarchs. The veto, once conceded by tradition to the Emperor, the King of France and the King of Spain, was abolished by the newly elected Pope Pius X, who imposed the penalty of excommunication upon anyone who would dare to introduce a veto, or otherwise interfere in the election of the Roman Pontiff. Pope Pius X further decreed that all cardinals should take an oathat the beginning of the conclave, promising not to aid any civil power in an attempt to influence the election of the pope. Puzyna was decorated with the Grand Cross of the Order of Saint Stephen of Hungary in 1904. He was a member of the Sacred Congregation Consistorial, the SC of Bishops and Regulars, the SC of the Index, the SC of Indulgences and Relics, and the SC of Studies. Jan Cardinal Puzyna de Kosielsko died in Kraków in 1911, five days before his 69th birthday.
