A criminal case in Toronto made history this week when a member of the city's police force was charged with second-degree murder, the first time a Toronto officer has had to answer a murder charge for actions taken while on duty.

The charge against the officer was upgraded from manslaughter following an investigation by Ontario's Special Investigations Unit into the shooting death of Eric Osawe, 26, during a September 2010 police search.

We take a look at what the change in charges means legally.

Canadian law distinguishes between justifiable, accidental and culpable homicide. If a death is deemed a culpable homicide, it generally falls under one of four categories.

First degree murder

Definition: A culpable homicide that is planned and deliberate — both aspects must be demonstrated in order for the homicide to be considered first-degree murder.

Some homicides are automatically considered first-degree murder — even if they were not intentional or planned:

• The killing of a police officer or prison employee on duty.
• A killing committed in the course of one of the following offences: hijacking, sexual assault, sexual assault with a weapon, aggravated sexual assault, kidnapping, forcible confinement, hostage taking, terrorism, intimidation,criminal harassment, any offence committed on behalf of a criminal organization.

Sentence: First -degree murder carries an automatic life sentence with no possibility of parole for 25 years. Offenders who are paroled remain on parole for the rest of their life, even after their release from prison, meaning they must report to a parole officer and are subject to the conditions of their parole. If they break the conditions of their release, they are sent directly back to prison without a hearing.

Second-degree murder

Definition: A deliberate killing carried out without planning that does not fall under any of the categories of first degree murder.

Sentence: The minimum sentence is life in prison with no parole for 10 years, but sentences can be as long as life in prison without parole for 25 years. The date of parole eligibility is at the judge's discretion.

Manslaughter

Definition: A homicide committed without the intention to cause death, although there may have been an intention to cause harm. There are two broad categories of manslaughter:

Unlawful act — when a person commits a crime that unintentionally results in the death of another person. For example, an individual punches someone in the face, and that person dies of his or her injuries, or someone fires their gun carelessly in public and unintentionally shoots a bystander.

Criminal negligence — when the homicide was the result of an act or a failure to act that showed wanton or reckless disregard for the lives of others. An act is generally considered negligent if a reasonable person would have foreseen that the action would endanger a life. A failure to act can only be considered negligence if a person had a duty imposed by law to act — it does not apply, for example, to bystanders who see a person in distress and don't help.

In some instances, a murder charge may be reduced to manslaughter if alcohol or other substances are found to have impaired the mental faculties of the perpetrator or if the homicide was committed in the heat of passion resulting from provocation, which is defined as a wrongful act or insult that would deprive an ordinary person of the power of self-control.

Impaired driving causing death is a separate offence under the Criminal Code that carries a maximum punishment of 14 years in prison.

Sentence: Manslaughter carries no minimum sentence, except when it is committed with a firearm, in which case the minimum sentence is four years in prison. Sentences vary from probation to life in prison.

Infanticide

Definition: When a mother causes the death of her newborn child, either willfully or through an act of omission, while in a mentally disturbed state resulting from the effects of giving birth to the child.

Sentence: No minimum sentence, but the maximum sentence is five years in prison.