What attracted you to the story of Granville Sharp and the Somerset case?

I have spent the last 20 years as an animal-rights lawyer. In my process of trying to understand whether non-human animals should have basic legal rights and if so which ones, I began to ask, Why should humans have rights? When did humans get rights? Which are the most fundamental? What is it about being human that qualifies us for rights?

As I began to look into those questions, I kept running into the question of human slavery. Why is it that some humans enslaved others, so that instead of viewing them as legal persons with rights, they were viewed as "things" without any rights at all that existed for the benefit of legal persons. And then how did that change? How did legal things become legal persons? How did slaves become free? How did they get rights?

That kept leading me back to the Somerset case where, instead of having a civil war like we had in the United States to free the slaves, England managed to free the slaves through a single judicial decision. It's a lot better to have social change come about through judicial decisions or legislative change than through civil war. So I kept coming back to Somerset and I became engrossed in the details of the world of Granville Sharp, Lord Mansfield, and James Somerset.

Is the story of the Somerset case just a good tale? Or does it present us with a usable past that can help us deal with issues today?

Both. It's an interesting tale. The characters are eccentric, dedicated, intelligent, certainly immersed deeply into their own time.

Granville Sharp is a fervent believer in a particular sort of Christianity who indeed believes in the literal truth of the Bible. But he's fiercely anti-Catholic—doesn't ...