One of the most neglected tools for understanding the Constitution is also one of the most important: The Law of the 18th century.

The Constitution is a legal document. It was written mostly by lawyers. It was explained to the ratifying public mostly by lawyers. And that public was exceptionally well-versed in law: As Edmund Burke pointed out in his 1775 speech on Reconciliation with America, “In no country perhaps in the world [as America] is the law so general a study.” And while most of the Constitution is written in straightforward lay language, it does contain some important legal terms of art.

Yet very few writers on the Constitution – even law professors – have made much of an effort to access 18th century law.

Here are a few examples of constitutional words and phrases that writers on the Constitution have puzzled over—and often misunderstood. And unnecessarily misunderstood, because each of these words and phrases had just one or two clear and accepted meanings in 18th century law and legal documents:

* Advice and Consent

* Commerce

* Due Process

* Habeas Corpus

* High . . . Misdemeanors

* Necessary and Proper

* Privileges and Immunities

* Aid and comfort

* Law of Nations

* Ex post facto

* Bill of Attainder

You can find out what some of these meant by checking out Constitutional Nuggets. You can learn about the rest from my new book, The Original Constitution: What It Actually Said and Meant.

If you’d like to know more about how to access 18th century law, check out Forgotten Treasures: Reseaching the Original Understanding of the U.S. Constitution.

cross-posted from the Independence Institute’s “Our American Constitution” blog.