Perjury, also known as forswearing, is the willful act of swearing a false oath or affirmation to tell the truth, whether spoken or in writing, concerning matters material to a judicial proceeding. That is, the matter lied about would affect the outcome of the case. It is not considered perjury, for example, to lie about one's age, unless that person's age is a key factor in proving the case, such as eligibility for old age retirement benefits.

Perjury is considered a serious offense as it can be used to usurp the power of the courts, resulting in miscarriages of justice. In the United States, for example, the general perjury statute under Federal law defines perjury as a felony and provides for a prison sentence of up to five years. In the United Kingdom a potential penalty for perjury is a prison sentence of up to 7 years. However prosecutions for perjury are rare.

The rules for perjury also apply when a person has made a statement under penalty of perjury, even if the person has not been sworn or affirmed as a witness before an appropriate official. An example of this is the United States' income tax return, which, by law, must be signed as true and correct under penalty of perjury (see ). Federal tax law provides criminal penalties of up to three years in prison for violation of the tax return perjury statute. See .

Statements of interpretation of fact are not perjury because people often make inaccurate statements unwittingly and not deliberately. Individuals may have honest but mistaken beliefs about certain facts or their recollection may be inaccurate. Like most other crimes in the common law system, to be convicted of perjury one must have had the intention (mens rea) to commit the act, and to have actually committed the act (actus reus).

In some countries such as France, Italy, and Germany, suspects cannot be heard under oath or affirmation and thus cannot commit perjury, regardless of what they say during their trial.
Subornation of perjury, attempting to induce another person to perjure themselves, is itself a crime.

Famous people who have been convicted of perjury

• Jonathan Aitken, British politician, who was a member of John Major's cabinet, was sentenced to 18 months imprisonment for perjury.

• Jeffrey Archer, British novelist and politician, was sentenced to 4 years imprisonment for perjury

• Silvio Berlusconi was convicted of lying under oath to a court. He changed Italian law, allegedly to give himself an amnesty.

• Mark Fuhrman, Los Angeles Police Department detective, entered a no contest plea to a perjury charge relating to his testimony in the murder trial of O. J. Simpson.

• Marcus Einfeld, former Justice of the Federal Court of Australia, for lying on oath to avoid losing his drivers licence.

• Alger Hiss, alleged Soviet spy who worked for the United States Department of State, was sentenced to 5 years imprisonment for perjury and served 44 months.

• Dr. Cecil Jacobson, American fertility doctor.

• Marion Jones, American athlete, was found guilty of two counts of perjury in 2008.

• Lil' Kim, American rapper.

• Lewis "Scooter" Libby, former Chief of Staff to the Vice President of the United States under Dick Cheney and assistant to President George W. Bush, was convicted of two counts of perjury, along with other offenses in connection with the Plame affair. President Bush used his executive clemency power to commute the jail sentence.

• Bernie Madoff, the former Chairman of the NASDAQ stock exchange and the admitted operator of the Ponzi scheme that might be "the largest investment fraud in Wall Street history".

• Mike Martin, Texas state Representative, pleaded guilty to a perjury charge resulting from his testimony before a grand jury investigating his attempted assassination in 1981.

• Michele Sindona, along with other charges of fraud, false bank statements, and misappropriation of bank funds

• Martha Stewart was convicted of conspiracy to commit perjury (although not perjury itself), and for making a false statement to a federal agent.

Famous people accused of perjury

Famous people who have been accused of perjury include:

• Roland Burris, freshman Democratic United States Senator from Illinois has been accused of perjury as a result of his testimony before the Illinois State Legislature during the investigation into his dealings with the now-impeached former Democratic Governor Rod Blagojevich.

• Long-serving Queensland premier Joh Bjelke-Petersen was charged with perjury as a result of the Fitzgerald Inquiry but a hung jury caused the trial to be abandoned.

• Barry Bonds has been indicted by a federal grand jury for allegedly perjuring himself in testimony before a grand jury in 2003 as part of the BALCO steroid scandal, in which he denied using any performance-enhancing drugs.

• Former Houston Police Chief Clarence Bradford - was indicted by Harris County District Attorney Chuck Rosenthal for alleged swearing at fellow Houston Police officers; perjury charge was dismissed due to the lack of evidence and/or fabricated charges.

• Former U.S. President Bill Clinton was accused of perjury and as a result was impeached by the House of Representatives on December 19, 1998. The Senate acquitted him on the false testimony charge as cause to remove him from office by a vote of 55 not-guilty votes to 45 guilty votes. No criminal charges were ever brought, though Clinton was later fined for contempt of court and, after thorough negotiations, agreed to be temporarily disbarred to avoid the possibility of a lengthy criminal trial.

• Joseph Ejercito Estrada, the 13th President of the Philippines, was accused of perjury.

• Alberto Gonzales, the former attorney general of the United States, is under investigation by an independent counsel for lying to congressional committees about the firing of 8 U.S. attorneys (see:Dismissal of U.S. attorneys controversy).

• On March 24, 2008, Detroit mayor Kwame Kilpatrick was criminally indicted for possible perjury and obstruction of justice charges concerning sexually-charged text messages sent to his chief of staff, Christine Beatty (both were married at the time). Both are suspected of lying about the existence of those messages under oath while testifying in a whistleblower lawsuit against the city of Detroit, which cost the city 8.4 million dollars. According to the Detroit Free Press, he was the third mayor of the city to be criminally charged.

• Rafael Palmeiro faced perjury charges (but was never charged) for possible false testimony in front of Congress regarding steroid use in professional baseball. Roger Clemens is currently under investigation for the same.

• Tommy Sheridan, Scottish politician, and his wife Gail, their trial is due to take place at some point in 2010.

• Paul Burrell - accused of being less than truthful at inquest of Princess Diana, but no charges brought

• Eddie Price, Jr. - mayor of Mandeville, Louisiana, and former Tulane Green Wave American football running back

See also

• Anatomy of a Murder

• Testilying