Mr. Rosić graduated from the Faculty of Law in Novi Sad in 1968. After this, he was employed in the Municipal Court in Livno as a law clerk. After passing the bar exam, he was appointed as a Judge at the Municipal Court in Livno. During this time, he worked in all departments of the Court (non-contentious, civil and criminal sections). He also went on to serve as the President of the mentioned Court.  In 1974, he was appointed as a Judge of the County Court in Banja Luka and worked on different cases (the first-instance and the second-instance criminal cases). He served as the President of the County Court in Banja Luka from 1984 until 1993, when he was appointed the Minister of Justice in the Government of the Republika Srpska. He was appointed the Judge of the Constitutional Court of the Republka Srpska n 1995 and, in 1998, he was appointed the President of the Supreme Court of the Republika Srpska.  

He participated in several projects on drafting the laws and dealing with certain legal issues, particularly since the beginning of the judicial system reform in 2000.  He published a number of texts in various journals of the associations of the judges and prosecutors, in particular concerning the independence of the courts and judges in accordance with the European standards.  He also published texts on the role and place of a judge in the regular judicial system of the Republika Srpska and Bosnia and Herzegovina.  

He served as a Judge of the Constitutional Court of Bosnia and Herzegovina from October 2003 to November 2006.