The Presidential Oath of Office is prescribed in accordance with the U.S. Constitution. When Obama is sworn in for the second time as President of the United States today, he does have the option not to swear but instead to affirm. The language of the Constitution allows every incoming President to make this choice: as it lays out in Article II, Section I: “Before he enter on the execution of his office, he shall take the following oath or affirmation. ‘I do solemnly swear or affirm that I will faithfully execute the office of president of the United States and will to the best of my ability preserve, protect and defend the Constitution of the United States.'” While the reasons for this choice of oath or affirmation aren’t documented in the Constitution or elsewhere, it’s commonly understood that it dates back to the beliefs of certain groups of Christians, notably the Quakers, Moravians, and Jehovah’s Witnesses, who take very literally certain Scriptural injunctions that forbid you to swear on oath. As set out in the Sermon on the Mount: “But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation” (James 5:12, KJV); swearing is also prohibited by Matthew 5:33-37.
Franklin Pierce was the only president known to use the word affirm rather than swear (in 1853), and hence he took an affirmation of office, rather than an oath. Herbert Hoover, because he was a Quaker himself, is thought by many to have used “affirm”, but newsreels confirm that he swore, like all but one of his predecessors. Richard Nixon, also a Quaker, chose to swear rather than affirm. (Incidentally, although not included in the text laid out in the Constitution, it is customary for modern presidents to say “So help me God” at the end of the oath.)
So, what is the difference between swearing and affirming? Legally and semantically there is no real difference: they both represent an official and legal promise to execute or fulfill a task — usually an important political or legal duty to a court or country. An oath is usually sworn with reference to an object or text — such as the Bible or the Constitution — and therefore to an external religion or set of principles; an affirmation, on the other hand, refers to one’s own honor, represented often by one’s own name. In English courts of law, the right of Quakers and Moravians selected as jurors to affirm rather than swear was introduced under the Quakers and Moravians Act of 1833, and it was soon extended to anyone who wishes to do so — and no reason for choosing to affirm needs to be given. As well as the Christian groups already mentioned, this option to affirm is a Godsend to atheists and agnostics.
When I was selected for a jury while doing my civic duty at the Old Bailey in the early ’80s, I was proffered the Bible on which ten men and women before me had sworn “by almighty God” to “try the defendant and give a true verdict according to the evidence”, as read from a printed card also given to each juror. (The defendant in question was accused of a gruesome crime and faced charges ranging from grievous bodily harm to attempted murder.) Even in my young mind — I was barely eligible for jury service — I understood that taking such a serious oath with reference to a deity or religion that was outside my field of meaning or understanding was in some way dishonorable, or even dishonest, and it seemed to contradict the very purpose of the oath. So I chose to exercise my right to affirm, sending the clerk of the court scurrying away to find the printed card for affirmations. I didn’t realize at the time that this election to affirm is not at all common (or at least it wasn’t at that time at the Old Bailey), and therefore the appropriate card wasn’t near at hand. As I waited — standing alone before the judge, the bewigged barristers and other court officials, and the defendant himself — I came to realize why people don’t generally choose to exercise this linguistic right: it singles you out. Especially in the solemn and hallowed halls of Great Britain’s most famous court of justice, where notorious criminals have been sent to their deaths and wronged innocents have been famously absolved, you don’t want to draw attention to yourself and stand out from any crowd — particularly not from those twelve good men and true whose job it is to deliver blind justice. English jurors are unnamed and anonymous — even post trial — and the idea of asserting their own identities, ideas, beliefs or theories outside the deliberation room are anathema to the English justice system. As this realization settled in, and I began to question my own reasons for choosing to affirm, the flustered clerk returned to the court and pushed the pagan affirmation card into my hand. I stated my name, and declared that I did “solemnly, sincerely and truly declare and affirm that the evidence I shall give shall be the truth the whole truth and nothing but the truth.” As I came to the end of the statement, glad to know that I would soon be seated again alongside my fellow jurors, it dawned on me (and to the court) that I had been affirmed not as a juror but as a witness. The barrister for the defence leaped to his feet and demanded to approach the bench. Minutes seemed to turn into hours as the judges and lawyers argued over whether I could be dismissed from the jury after reading the wrong affirmation; was I technically a juror at that point, having been sworn into the court, or did the defendant — who now knew my name — still have the right to reject me, as he now wanted to do? Meanwhile I continued to stand, mortified and alone before the court. I was eventually affirmed as a juror, and at the end of the harrowing trial, we the jury convicted him of his dreadful crime and sent him to prison for many years. The trial was ultimately more grueling than my swearing in, but it was nevertheless something of an ordeal because I had chosen to utter a few words that were different.