Mental states that determine the degree of guilt or culpability in criminal law are generally classified from highest (most worthy of blame or punishment) to lowest as: (1) intentional; (2) knowing; (3) reckless; and (4) criminal negligence.

A person acts with criminal negligence, or is criminally negligent, with respect to circumstances surrounding his conduct or the result of his conduct when he ought to be aware of a substantial and unjustifiable risk that the circumstances exist or the result will occur. The risk must be of such a nature and degree that the failure to perceive it constitutes a gross deviation from the standard of care that an ordinary person would exercise under all of the circumstances, as viewed from the accused person’s standpoint at the time of the alleged criminal negligence.

Criminal offenses or crimes often specify the culpable mental state the prosecution is required to prove to convict a defendant of the offense. These culpable mental states are generally defined in the relevant state or federal statutes—usually in the penal or criminal code.

In Pennsylvania, the mental state of an individual at the time of committing a crime is crucial in determining their degree of guilt or culpability. The mental states are ranked from most to least blameworthy as follows: (1) intentional, (2) knowing, (3) reckless, and (4) criminal negligence. Criminal negligence in Pennsylvania is defined as not being aware of a substantial and unjustifiable risk that one's conduct may lead to certain circumstances or results, which represents a significant departure from the standard of care an ordinary person would exercise. This risk must be apparent from the perspective of the accused at the time of the alleged negligence. Pennsylvania's criminal statutes, which can be found in the Pennsylvania Consolidated Statutes, specifically the Crimes Code (Title 18), outline these mental states and the requirements for proving them in court. To secure a conviction, the prosecution must demonstrate that the defendant acted with the requisite culpable mental state as defined by the relevant offense in the statute.