When President Bush and Vice President Cheney testified before the 9/11 Commission yesterday, they were not required to raise their right hands and swear “to tell the truth, the whole truth, and nothing but the truth.” When National Security Adviser Condoleezza Rice appeared before the commission earlier this month, however, she was compelled to testify under oath. How and when did the oath originate?

The tradition of requiring witnesses to swear an honesty oath likely traces back to Roman times. Urban legend contends that male Romans had to squeeze their testicles while vowing to tell the truth, which is why the Latin word for witness is testis. Latin scholars have debunked this colorful claim, pointing out that testis more likely comes from the Ancient Greek for “three”—a witness being a third observer of events. Still, the orator Cicero alluded to the importance of legally binding oaths in De Officiis, and the Law of the Twelve Tables, the earliest of codification of Roman law, stresses that perjurers “shall be hurled down from the Tarpeian Rock.”

The word “oath,” however, comes not from Latin, but rather Anglo-Saxon. The Anglo-Saxons used oaths not only to swear fealty to feudal lords, but also to ensure honesty during legal proceedings and transactions. When the Anglo-Saxon king Athelstan codified Britain’s laws around A.D. 930, he included a section requiring that the sale of chattel be witnessed by a neutral third party, who would take an oath to act truthfully and in the law’s best interest. The phrase “the truth, the whole truth, and nothing but the truth” is believed to have initially been coined in Old English, and to have become a staple of English trials by approximately the 13th century.

Despite the early addition of witness oaths to the English common law tradition, witnesses faced no codified penalties for perjury until the mid-16th century. Prior to that, it was believed that the specter of God’s vengeance alone was enough to coax witnesses into telling the unvarnished truth.

The earliest English settlers in America brought over the tradition of the witness oath; Noah Webster, for example, refers to the “whole truth” oath in a 1787 essay. The 1856 edition of Bouvier’s Law Dictionary notes that, after swearing the oath, witnesses were expected to kiss the Bible.

Courts are no longer so strict about ensuring that oaths contain a religious element. Early Quakers were the first Americans to object to the witness oath, citing a prohibition in James 5:12 against any form of swearing. (“But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath.”) More recently, some atheists have voiced discomfort at the prospect of having to swear on a Bible or mention God. As a result, a witness can request to affirm, rather than swear. A typical affirmation used in U.S. District Courts goes:

You do affirm that all the testimony you are about to give in the case now before the court will be the truth, the whole truth, and nothing but the truth; this you do affirm under the pains and penalties of perjury?

Witnesses of non-Judeo-Christian faiths can also ask to substitute an alternate text for the Bible. And atheists can ask to affirm atop a plain black book.

The most curious challenge to the oath in recent years occurred in U.S. v. Ward, a tax-evasion case involving a Las Vegas publisher named Wallace Ward. For reasons known only to him, Ward insisted on replacing the word “truth” with the phrase “fully integrated honesty.” The initial court refused to let him testify, but on appeal in 1992, the Ninth Circuit Court of Appeals ruled 2-1 that Ward had aptly demonstrated “a moral or ethical sense of right and wrong” with his proposed words.

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