Prof. Amusa holds the LL.B. degree of University of Ibadan and LL.M., M.Phil. and Ph.D. degrees in Law from Obafemi Awolowo University, Ile-Ife. He was called to the Nigerian Bar in 1989. He worked in the Ministry of Justice, Ibadan Oyo State where he rose to the post of Principal Legal Officer. He started his teaching career in 1995 at Ogun State University, Ago-Iwoye before he moved to the University of Lagos in 1999. He rose through the ranks and became Professor. He teaches Law of Evidence and Administrative Law. His research interest also includes Constitutional Law and Criminal Law. He is a fellow of the Institute of Security, Nigeria. He has served as external examiner to several Universities within and outside Nigeria. He was acting Head of Department of Public Law between 2016 and 2018. He served as Acting Head of Department (2016-2018) and Head of Department, Public Law (2020-2023).