While negligence alone can cause serious problems, criminal negligence is more significant. If a person behaves in such a reckless way so that it is unmistakably clear that a reasonable individual would not behave in the same way given the same circumstances, that person could be charged with criminal negligence. A person may be charged with negligence if he or she behaves a careless way that does not necessarily indicate criminal activity. However, there are instances of negligence in which a person acts in an obviously imprudent and uncontrolled way which almost always results in harmful and (usually) destructive behavior.

Someone could fairly question what makes a person considered reasonable or unreasonable. Although it is somewhat ambiguous and subjective, the decision is up to the court. The court determines whether or not the defendant acted in a criminally negligent way. Because it can be a rather subjective topic, the court must have evidence that the defendant's behavior was clearly negligent beyond rationality and beyond accident. If the defendant is found to have mental disabilities, the court may not rule that the behavior was criminally negligent. In addition, since children are not held under the same considerations as adults because of their age and maturity, the court does not judge a child's actions the same way.

There are several standard example of criminal negligence. Intoxicated drivers are often convicted of the behavior. DUI and DWI charges are not necessarily interchangeable, although they could be in some circumstances. DWI (Driving While Intoxicated) refers strictly to alcoholic influence on a driver, whereas DUI includes any sort of drug or alcohol stimulus. Any time a person consumes alcohol and gets behind a wheel of a vehicle, there is an added measure of potential danger because alcohol makes a person less discerning, aware, and rational. Therefore, it is no surprise that intoxicated drivers are more likely to drive carelessly, cause an accident, and be charged with criminal negligence. The other behavior that is often deemed criminally negligent is that which causes a child to be put in grave danger. Child neglect is not necessarily criminally negligent behavior, since it is more passive than active. However, if an adult actively puts a child in a particularly harmful situation, the adult may face criminal charges.

A person will not be charged with criminal negligence for doing something that was necessary. Sometimes deaths or highly dangerous circumstances are inevitable; there are times when no amount of preparation or provision can stop a tragedy. A person will not be held criminally guilty when responsible for those kinds of accidents. A person will only be face charges of criminal negligence when it is shown that he or she chose to act in a certain reckless way, seriously injured or killed someone else, and was indifferent to the outcome of that carelessness.

One factor which may play a part in determining criminal negligence in cases of a person's death is mens rea. The term means "guilty mind" in Latin and pertains to the intellectual involvement in the behavior. A person who deliberated, premeditated, or desired to hurt another person would be charged with mens rea considerations. Although behaviors involving criminal negligence do not necessarily imply that the defendant premeditated the action (the actus reus), it does not disprove it. The very fact that the defendant carried out whatever action it was is enough reason to charge him or her with gross negligence—criminal negligence. For example, an intoxicated driver who accidentally kills a person by vehicular manslaughter may be charged with criminal negligence, even if he had not desired to kill anyone. Therefore, the gross negligence—not necessarily malicious deliberation—is what makes a defendant guilty.