Courts of cassation do not re-examine the facts of a case; they only interpret the relevant law.
In this way, they differ from systems that have a supreme court that can rule on both the facts of a case and the relevant law.
The term derives from the Latin cassare, "to reverse or overturn".
In contrast, in France, for instance, courts of appeal hear cases on the facts and the law also, and only in the higher court of cassation is examination confined to matters of law.
In this sense, a petition for a writ of certiorari is akin to a pourvoi en cassation [fr].