Mr. Petrosyan is a legal expert. He is the Head of the Department of Law at the Yerevan College of Law, Economics and Management and lecturer in Municipal Law and Administrative Proceedings at the  Law Department of the Yerevan Northern University.

Since 2015 Mr Petrosyan has been  a member of the expert working group to  revise of the Law on Local Self-Government  of the Republic of Armenia.  He is also the co-author of the Law on Local Duties and Fees which was adopted in December 2016 and the Draft Law on Intercomunity Unions, which is pending adoption by the National Assembly of Armenia.