Professor Coughlan's primary teaching area is Criminal Law and Procedure. For many years, he coached competitive moot teams. Professor Coughlan has taught Constitutional Law, Health Law, and Medical Ethics (in the Faculty of Medicine), as well as Introduction to Law (a course offered by the Law School to non-law students).

Professor Coughlan's research interests include criminal law and procedure, law and technology/privacy – particularly as it intersects with criminal law issues – and interdisciplinary work on treatment of the elderly/adult protection. He is actively involved in efforts to have the federal government update the Criminal Code. Professor Coughlan has published 25 books and roughly 100 articles and book chapters. He is co-editor of and writes regular case annotations for the Criminal Reports and is a co-author of the National Judicial Institute Criminal Law Essentials eletter. He is also co-editor of the IT.Can Newsletter on Canadian information technology law developments.