Swearing in is the process of holding witnesses accountable for their official statements, as in a court proceeding such as a criminal or civil trial. While a witness is sworn in, everything they say must be true, or else they can be charged with perjury.
In Christian countries such as the U.S., a witness will place one hand on the Bible and raise the other hand, though the Bible is rarely used in court proceedings today. A common oath taken is,
The answer is,
Officials are often sworn into office in a similar way.
America's first Muslim congressman, Keith Ellison (D - Minn.), said he would carry a Koran to his swearing-in ceremony.[1]