The Supreme Court administers the oath to new presidents on Monday, as Trump gets inaugurated.

The presidential and vice-presidential oaths of office will be delivered at Monday's inauguration, with top members of the three branches of government coming together in a rare display of national unity and tradition. A rookie, perhaps with funny hats, will be an indispensable part of the ceremonies.

The tradition of administering oaths to President-elect Trump and his No. 2, JD Vance, will continue with Chief Justice John Roberts and Justice Brett Kavanaugh. The other seven members of the high court are expected to attend the event in the Capitol Rotunda, all in their judicial robes.

Despite any political differences, they will not be apparent at this formal and respectful event. The president will likely first thank the chief justice, but an underlying sense of tension persists.

In 2016, Trump attacked a federal judge during his first presidential campaign, calling him an "absolute disaster." This will be Trump's fifth presidential swearing-in, his second with Roberts.

Usha Vance, who will soon become the second lady of the United States, previously worked as a clerk for Kavanaugh when he served as a judge on the U.S. Court of Appeals in Washington.

Usha Vance received a strong job recommendation from Kavanaugh for a prestigious law clerkship at the Supreme Court with Roberts.

In an interview with "Fox and Friends" in August, Usha Vance praised Kavanaugh as a "good boss" and a "decent person" who had a diverse workforce.

"My experience working for him was overwhelmingly positive," she added.

Recent justices, including Sandra Day O'Connor, Ruth Bader Ginsburg, and Clarence Thomas, have performed similar vice-presidential swear-in honors.

In 2005, Vice President Dick Cheney was sworn in by then-House Speaker Dennis Hastert, who is not typically the one to handle such duties.

In 2017, Mike Pence was sworn in as vice president for Trump's first term, with Thomas officiating the ceremony.

Justice served

The Constitution mandates that executive officers, including the president, as well as members of Congress and federal judges, must take an oath or affirmation. However, there is no requirement for Supreme Court justices to administer this oath. During presidential inaugurations, they typically do so, although this is not always the case.

When George Washington was inaugurated as the first President of the United States in 1789, the Supreme Court had not yet been established. As a result, New York's highest-ranking judge administered the oath of office to Washington at Federal Hall on Wall Street. Four years later, Associate Justice William Cushing swore in Washington for a second term, marking the beginning of the Supreme Court tradition.

The first outdoor inauguration took place in 1817 when James Monroe was sworn in outside the Old Brick Capitol. This was due to the original Capitol being burned by British troops during the War of 1812. The site where Monroe took the oath is now occupied by the Supreme Court, which opened its building in 1935.

John Marshall, widely recognized as the most influential chief justice in U.S. history, handled duties over 200 years ago and participated in a record nine swear-ins, from Thomas Jefferson to Andrew Jackson. For Roberts, this will be his fifth.

The Constitution specifies the precise language for the 34-word oath of office: "I 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."

Judges often include the phrase "so help me God" in their oaths, although it is not legally or constitutionally required. Unlike other federal oaths, this phrase is not standard procedure. While some historians believe that President Washington set a precedent by adding it during his first acceptance, contemporary accounts do not mention any ad-libbing.

In 1861, Abraham Lincoln is said to have made a spontaneous statement, and other presidents have followed suit. During the oath of office, a Bible is traditionally used, with the president placing one hand on it while raising the other.

Lincoln and Taney had a mutual animosity, which was evident during the oath-taking ceremony just before the Civil War. Several historians have stated that Lincoln secretly issued an arrest warrant for Taney later that year, but the warrant was never served.

President Barack Obama used Lincoln's Bible for his two swear-ins.

Trump is expected to again use the Lincoln Bible and a family Bible.

Getting it right

In 2009, Roberts administered his first presidential oath but deviated slightly from the text, prompting a re-administration the next day in a private White House ceremony for protective purposes.

Despite the lengthy Jan. 20 ceremonies at the Capitol, Obama officially assumed the presidency under the 20th Amendment at noon.

Michael Newdow, a California atheist, and several non-religious groups sued in federal court to stop Roberts from making Obama repeat the "so help me God" phrase, arguing that the words violated the constitutional prohibition against government "endorsement" of religion.

No legal challenges are expected this time as the high court ultimately rejected the lawsuit.

In 2013, Justice Sonia Sotomayor swore in Biden for a second term as vice president. Now, Vice President Harris has asked her to do the honors again, citing their shared history as government prosecutors.

Pence stated on Planet Chronicle that he used the late President Ronald Reagan's family Bible, expressing his deep gratitude to the president-elect for his confidence and the American people for their support.

Trump deviated from tradition by not attending the inauguration of his successor four years ago.

Since 1965, Lyndon Johnson's swear-in marked a change from tradition. His wife Claudia, known as Lady Bird, held the Bible, a job previously managed by the high court's clerk. Spouses have since had the honor, and Melania Trump and Usha Vance are expected to continue that role.

In 1941, Elmore Cropley, a clerk, accidentally dropped the Bible during President Franklin D. Roosevelt's third inauguration, causing a repeat of a previous goof.

What to wear, what to say

At the inauguration, it is easy to identify the justices, who are typically concealed from public view in the camera-free court. They are introduced as a group, enter wearing their black robes, often over bulky winter coats, and are positioned prominently on the platform on the West Front of the Capitol.

In 1801, before Marshall assumed the court, the justices wore red robes with fur trim and white wigs in public. Since then, the American judicial standard has been a simple black silk robe without a wig.

The large black skullcaps worn by some justices have no brims and can be made of wool, silk, or nylon. To avoid resembling a Jewish yarmulke, these hats are usually pleated upward. One federal judge privately told Planet Chronicle that this style made him look like he was wearing a dirty napkin.

Because of the expected frigid weather, the skullcaps may not be a priority during the indoor inauguration ceremony.

Since the 16th century, robes have been used in British courts and for at least a century in the United States. These garments are worn exclusively by judges during formal ceremonies, but not in court.

The hazy official records do not provide much information on the hats, but Chief Justice Edward White proudly wore one in 1913 during Woodrow Wilson's inauguration. The "age of the skullcap" reached its peak in 1961 when seven out of the nine justices wore them at the bitterly cold inauguration of President John F. Kennedy.

No current or former woman justice has ever worn a locket.

In an interview, Scalia explained why he preferred skullcaps. He said, "I wear the old hats that judges used to wear during inaugurations. Although it looks ridiculous, it's a tradition. It's a silly-looking hat."

The St. Thomas More Society of Richmond, Virginia, presented Scalia with a headgear resembling one worn by St. Thomas More as a gift.

Not surprisingly, given his role as an unofficial historian of court procedure and tradition, the late Chief Justice William Rehnquist also wore them.

In 2005, he made a dramatic appearance at the inauguration despite suffering from thyroid cancer, and despite speculation that he might not be able to attend, he assured officials he would be there and kept his word.

The 81-year-old chief, who had been away from the public eye for three months while receiving chemotherapy, was introduced to the audience before President George W. Bush took the oath. He walked slowly to the podium with a cane, wearing a dark baseball cap, and did the honors. Despite having a trachea tube in his throat, which was hidden by a scarf, his voice was clear but raspy.

Bush was wished good luck by Rehnquist before being swiftly escorted out of the chilly room.

In 1997, Rehnquist presided over the impeachment trial of President Bill Clinton, who was accused of sexual harassment by Paula Jones. The justices had taken a private vote in Clinton v. Jones days earlier, ruling that the president could not refuse to testify in the ongoing civil lawsuit against him. This decision set off a chain of events leading to Clinton's impeachment trial.