Caroline Kennedy says that when she took a class at New York's Columbia Law School on civil rights, she wasn't quite sure what the Bill of Rights was.

"I'd heard of it, but I don't think I knew it was the first 10 amendments to the Constitution," Kennedy, 33, told People magazine in its Feb. 11 issue.That class inspired Kennedy, and schoolmate Ellen Alderman, 32, to write a book called "In Our Defense: The Bill of Rights in Action." The women took turns writing up each case, then edited each other's work.

The book is a collection of court cases illustrating the Bill of Rights, which was ratified in 1791. The book, to be published this month, celebrates the Bill of Rights' 200th anniversary.

"We don't realize how fortunate we are," Kennedy said.