The eighth commandment forbids:
false witness, perjury, and lying, the gravity of which is measured by the truth it deforms, the circumstances, the intentions of the one who lies, and the harm suffered by its victims;
rash judgment, slander, defamation and calumny which diminish or destroy the good reputation and honor to which every person has a right;
flattery, adulation, or complaisance, especially if directed to serious sins or toward the achievement of illicit advantages.
A sin committed against truth demands reparation if it has caused harm to others.