Sorry for the cut-n-paste, but, from wikipedia on criminal negligence...:
To constitute a crime, there must be an actus reus (Latin for "guilty act") accompanied by the mens rea (see concurrence). Negligence shows the least level of culpability, intention being the most serious and recklessness of intermediate seriousness, overlapping with gross negligence. The distinction between recklessness and criminal negligence lies in the presence or absence of foresight as to the prohibited consequences. Recklessness is usually described as a 'malfeasance' where the defendant knowingly exposes another to the risk of injury. The fault lies in being willing to run the risk. But criminal negligence is a 'misfeasance or 'nonfeasance' (see omission), where the fault lies in the failure to foresee and so allow otherwise avoidable dangers to manifest. In some cases this failure can rise to the level of willful blindness where the individual intentionally avoids adverting to the reality of a situation. (In the United States, there may sometimes be a slightly different interpretation for willful blindness.) The degree of culpability is determined by applying a reasonable person standard. Criminal negligence becomes "gross" when the failure to foresee involves a "wanton disregard for human life" (see the discussion in corporate manslaughter).
The test of any mens rea element is always based on an assessment of whether the accused had foresight of the prohibited consequences and desired to cause those consequences to occur. The three types of test are:
- subjective where the court attempts to establish what the accused was actually thinking at the time the actus reus was caused;
- objective where the court imputes mens rea elements on the basis that a reasonable person with the same general knowledge and abilities as the accused would have had those elements; or
- hybrid, i.e., the test is both subjective and objective.
The most culpable mens rea elements will have both foresight and desire on a subjective basis. Negligence arises when, on a subjective test, an accused has not actually foreseen the potentially adverse consequences to the planned actions, and has gone ahead, exposing a particular individual or unknown victim to the risk of suffering injury or loss. The accused is a social danger because he or she has endangered the safety of others in circumstances where the reasonable person would have foreseen the injury and taken preventive measures. Hence, the test is hybrid.