Omission (law)

In law, an omission is a failure to act, which generally attracts different legal consequences from positive conduct. In the criminal law, an omission will constitute an actus reus and give rise to liability only when the law imposes a duty to act and the defendant is in breach of that duty. In tort law, similarly, liability will be imposed for an omission only exceptionally, when it can be established that the defendant was under a duty to act or duty of care.

Criminal law

In the criminal law, at common law, there was no general duty of care owed to fellow citizens. The traditional view was encapsulated in the example of watching a person drown in shallow water and making no rescue effort, where commentators borrowed the line, "Thou shalt not kill but needst not strive, officiously, to keep another alive." (Arthur Hugh Clough (1819–1861)) in support of the proposition that the failure to act does not attract criminal liability. Nevertheless, such failures might be morally indefensible and so both legislatures and the courts have imposed liability when the failure to act is sufficiently blameworthy to justify criminalisation. Some statutes therefore explicitly state that the actus reus consists of any relevant "act or omission", or use a word that may include both. Hence, the word "cause" may be both positive in the sense that the accused proactively injured the victim and negative in that the accused intentionally failed to act knowing that this failure would cause the relevant injury. In the courts, the trend has been to use objective tests to determine whether, in circumstances where there would have been no risk to the accused's health or well-being, the accused should have taken action to prevent a foreseeable injury being sustained by a particular victim or one from a class of potential victims.

So, returning to the drowning example, the accused would be liable if the victim was a child in a pool with a water depth of six inches, or there was a flotation device nearby that could easily be thrown to the victim, or the accused was carrying a mobile phone that could be used to summon help.