Professor Green's research interests include constitutional theory, moral and political philosophy, legal obligation and authority, legal reasoning, and moral and legal issues surrounding sexuality.
- Freedom of speech, especially in connection with obscenity laws
- Sexuality and law
- Same-sex marriage
- Minority language rights
- Academic freedom
Professor Green has experience of working with the media. He has written a number of op-ed articles and has appeared on radio, including BBC Radio 4's Analysis.