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What Is The Common Law?

By Steven Wise

Last week I wrote that the goals of the Nonhuman Rights Project are to educate and persuade the judges of an American state high court that a nonhuman animal has the capacity to possess common law rights. The last six words, “capacity to possess common law rights,” contain three complicated ideas: “capacity to possess,” “common law,” and “rights.” Unless you have an idea of what those six words mean, you won’t understand what the Nonhuman Rights Project is trying to do. That’s why now, and over the next few weeks, I’ll briefly explain them.

Let’s start with the common law. The common law is what English-speaking judges around the world have been making for a thousand years in the process of deciding cases that turn on general legal principles, and when they’re not interpreting statutes or constitutions, regulations or treaties. American federal courts don’t use the common law. Neither does the state of Louisiana, which has a French civil law heritage, and Puerto Rico, which once used Spanish civil law. But the other 49 American states and the District of Columbia all use the common law.

How does a judge decide what the common law should be? Before the mid-Nineteenth Century American Civil War, Lemuel Shaw, one of America’s greatest common law judges, thought it consisted “of a few broad and comprehensive principles, founded on reason, natural justice, and enlightened public policy, modified and adapted to the circumstances of all the particular cases which fall within it.” That remains a pretty good definition and I use it today.

Shaw left out one thing, the influence on the development of the common law of cases that have been decided previously. That’s because he didn’t care about how previous judges dealt with some problem. But a lot of common law judges do. They value stability and certainty in the law, even when that law might be morally wrong or bad for society, and so they decide cases by determining how other judges have ruled then trying to do the same thing. But Shaw, and our other great common law judges, don’t do that. They struggle to determine the morally right thing to do or the best thing to do for society, each based on modern morality, experience, and scientific fact. Then they do it.

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