Comparative law is the study of differences and similarities between the law of different countries. More specifically, it involves study of the different legal systems in existence in the world, including the common law, the civil law, socialist law, Islamic law, Hindu law, and Chinese law. It includes the description and analysis of foreign legal systems, even where no explicit comparison is undertaken. The importance of comparative law has increased enormously in the present age of internationalism, economic globalisation and democratisation.

The birth of modern comparative law is generally attributed to Europe in the eighteenth century. However, prior to that, legal scholars (forerunners of today's comparativists and international lawyers) practiced comparative method. In Russian legal history, for instance, comparative method dates back to the sixteenth century.

According to the prevalent view, Montesquieu is regarded as the 'father' of comparative law. His comparative approach is obvious in the following excerpt from Chapter III of Book I of what many consider to be his masterpiece, De l'esprit des lois:

Richard Frank Hyland (July 26, 1900 – July 16, 1981) was an American rugby union player who competed in the 1924 Summer Olympics.

He was a member of the American rugby union team, which won the gold medal. Hyland also played college football at Stanford University, and went on to become a sportswriter for the Los Angeles Times.

Mary Ann Glendon (born October 7, 1938 Pittsfield, Massachusetts) J.D., LL.M., was the United States Ambassador to the Holy See (2008–2009), and is the Learned Hand Professor of Law at Harvard Law School. She teaches and writes on bioethics, comparative constitutional law, property, and human rights in international law. She is pro-life and "writes forcefully against the expansion of abortion rights."

Glendon graduated from University of Chicago Law School, where she served on law review.

Glendon is the author of Rights Talk; A Nation Under Lawyers, and A World Made New: Eleanor Roosevelt and the Universal Declaration of Human Rights. In 1994, she was a signer of Evangelicals and Catholics Together, an ecumenical document aimed at rapprochement between Catholics and Evangelicals. Glendon became the first female President of the Roman Catholic Church's Pontifical Academy of Social Sciences, when she was appointed by Pope John Paul II on March 9, 2004 (she was already a member of the academy since January 9, 1994).