Watch any courtroom drama on TV and you will definitely find a scene that shows an individual swearing or affirming to tell the truth under oath. Such scenes are also very important in real life but being under oath is not just limited to testifying in court. Understanding that you must tell the truth also applies to affidavits, depositions, and signing legal certificates; therefore, you can be under oath both when speaking and writing. However, what happens if you fail to tell the truth and deliberately lie? This is defined as perjury and is a crime according to California Penal Code 118-131 PC.
Perjury is a serious crime because the deliberate misrepresentation of facts during proceedings of the justice system can lead to serious consequences, such as the criminal conviction of an innocent person (and at the most extreme: capital punishment). Anyone can perjure themselves, and this includes law enforcement officers.
In order for a prosecutor to prove that you committed perjury, they must prove four key elements. First, the false statement (oral or written) was to have been made deliberately by the individual accused of perjury. For example, if the individual had just written a note for themselves without any intention of submitting it under oath, it would not count as perjury. Second, the individual must have known that their statement was false. If the individually accidentally gives a false fact, that is not perjury as they must have knowingly lied. Third, when giving that false statement, the individual knew they were under oath. Fourth, the false statement was a material fact, or is related to same. A material fact in a case is one that affects the outcome of legal proceedings or could influence it.
If the accused is found guilty of perjury, severe punishments as well as reputational costs apply. If you have previously lied under oath, it becomes difficult to establish yourself as a credible witness. If the punishment requires prison time, the accused can face up to four years in prison. However, depending on the context of the crime, some can face no prison time and instead face probation or fines.