Omission is the failure to act - this cannot make a person guilty of an offence. However, there are situations where an omission can give rise to liability in criminal law
an Act of parliament creates an offence involving an omission
a contractual duty exists
a duty exists because of a relationship between the victim and the accused
a duty toward the victim has been taken on voluntarily by the accused
a duty to act arises as a consequence of the accused's official position
a duty to act arises because the defendant has set in motion a chain of events