Perjury is the intentional act of swearing a false oath or falsifying an affirmation, to tell the truth, whether spoken or in writing, concerning matters material to an official proceeding. Perjury is considered a serious offense, as it can be used to usurp the power of the courts, resulting in miscarriages of justice. In Canada, those who commit perjury are guilty of an indictable offense and liable to imprisonment for a term not exceeding fourteen years. In some countries such as France and Italy, suspects cannot be heard under oath or affirmation and so cannot commit perjury, regardless of what they say during their trial. In the United States, Kenya, Scotland, and several other English-speaking Commonwealth nations, subornation of perjury, which is attempting to induce another person to commit perjury, is itself a crime.

Source: Wikipedia