Mr. Petrosyan graduated with a degree in law from Yerevan State University in 1965. He is a professor and PhD of Legal Sciences. He was awarded a Medal for Labor Excellence by the Presidium of the USSR Supreme Council in 1970.
From 1957-1958 he was a joiner in the Apanovka Station of Khazakh SSR. From 1958-1962 he was a turner in the Kirovakan Precise Machines Plant. From 1965-1966 he did his postgraduate studies at the Yerevan State University Law Department. From 1966-1970 he was a judge in the People's Court of Spitak Region. For the next fourteen years he was a professor in the Yerevan State University Law Department. From 19841988 he was a deputy dean. From 1988-1996 he was a dean and from 1991-2003 he was the head of the Civil Law Chair at the Yerevan State University Law Department.
From 1990-1995 he served in the Supreme Council (electoral district # 184). From 1992-1995 he was a member of Constitutional Committee and Working Group.
On May 25, 2003 he was elected to the NA from electoral district # 3 and he is currently the Chairman of the NA Standing Committee on State and Legal Affairs. He is a member of the “People's Deputy” Deputy Group and the Republican Party of Armenia.
Mr. Petrosyan is married and has four children.