In general a person under English law may walk along the beach and ignore with impunity the cries of a drowning fellow citizen. In fact, in many areas where there might be a moral obligation to speak or to act, the law permits an omission.
In the law of contract, simple reticence does not amount to fraud. If you are selling a car, and a prospective buyer comes along to view it with a friend, he may say, quite wrongly, to his friend "these Mark II models were all produced at Dagenham and have an excellent reputation". In such a situation you are not legally obliged, if you know better, to correct the misapprehension. Any contract that follows your sly silence cannot be invalidated by it. You must, though, remain, inexpressive because a nod, a wink or a shake of the head designed to induce the buyer to believe the truth of his observation will amount to false representation.
Silence could also make you liable for a misrepresentation if you fail to correct a statement which has ceased to be true by the time a contract is finalised. In one case where a medical practice was being purchased, it was a thriving concern when the buyer first made investigations but the patient list had dwindled drastically by the time the deal was to be signed - a fact the seller forgot to mention. The buyer was able to rescind the contract.
In civil law there is no general duty to lend assistance to those who need it, although the law says that if you negligently cause someone to be imperilled, you owe a duty of care to anyone who leaps in to rescue them. Thus, an employer whose unsafe method of cleaning a shaft caused workers to become gassed, was liable to the widow of a doctor who was killed trying to rescue them. This can be seen as transferring the cost of the negligence from the public purse to the negligent party - a tax on carelessness.
Article 2 of the European Convention on Human Rights guarantees the right to life, so it will be interesting to note whether, when the UK courts start to implement the Human Rights Act 1998, they impose the same duties to aid citizens in danger as exist in continental Europe.
Medico-legal developments have moved us pretty much in line with Arthur Hugh Clough's nineteenth-century observation in The Latest Decalogue: "Thou shalt not kill; but need'st not strive officiously to keep alive".
The House of Lords has ruled that it can be lawful for doctors to omit to give or to withdraw life-supporting medical treatment from a patient who is in a persistent vegetative state with no prospect of recovery or improvement. There is no absolute rule that medics must preserve a patient's life regardless of the circumstances.
The position taken by the criminal law was well encapsulated by Lord Macaulay a hundred years ago. He wrote that "to attempt to punish men by law for not rendering to others all the service which it is their [moral] duty to render to others would be preposterous".
He asked whether, if the rich man who refused to save the beggar's life at the cost of a copper was a murderer, was the poor man just one degree above beggary not also a murderer if he refused to share his hard-earned food?
There are, however, some situations where an omission to act will amount to a criminal offence. A motorist who, without reasonable excuse, fails to provide a police officer with a specimen of breath when required to do so will be committing an offence under the 1988 Road Traffic Act. By the same token, a police officer who wilfully neglects to perform his or her duty will be committing an offence - as one found out to his cost when he walked away from an incident in which someone was being kicked to death outside a nightclub. Parents are under a duty to their children to protect them, and spouses are under a duty to aid one another.
You are also under a duty if you assume responsibility for someone who is ill or infirm. If you subsequently leave him or her in the lurch and they die, you could be guilty of manslaughter.
Princess Diana has been eulogised and condemned but she was, by fairly common consent, a person who seemed to like helping others. On one occasion she apparently leapt out of her car on a bridge in Regents Park to rescue a man who had fallen into the lake.
It is therefore by particularly sharp contrast that, as she lay dying illuminated by flashbulbs, the commercial considerations impelling those photographing her demise exercised a greater pull on the snappers than the common humanity she exemplified in life.