It is a misapprehension of fact on the part of the person causing the injury to another. Such person is NOT criminally liable as he acted without criminal intent. Requisites: 1. The act done would have been lawful had the facts been as the accused believed them to be; 2. The intention of the accused in performing the act should be lawful; and 3. The mistake must be without fault or carelessness on the part of the accused. When defense of mistake of fact not applicable. 1. When there is mistake in identity; 2. When there is negligence on the part of the accused; or 3. When the accused committed a culpable felony.