One of the classic statements concerning negligence. Note the resort to a general theory of relations to justify the decision.
Lord Atkin said,
‘… The question is whether the manufacturer of an article of drink sold by him to a distributor, in circumstances which prevent the distributor or the ultimate purchaser or consumer from discovering by inspection any defect, is under any legal duty to the ultimate purchaser or consumer to take reasonable care that the article is free from defect likely to cause injury to health.
I do not think a more important problem has occupied your Lordships in your judicial capacity: important both because of its bearing on public health and because of the practical test which it applies to the system under which it arises.
…The law of [England and Scotland] appears to be that in order to support an action for damages for negligence the complainant has to show that he has been injured by the breach of a duty owed to him in the circumstances by the defendant to take reasonable care to avoid such injury.
In the present case… We are solely concerned with the question whether, as a matter of law in the circumstances alleged, the [defendant] owed any duty to the [claimant] to take care.
It is remarkable how difficult it is to find in the English authorities statements of general application defining the relations between parties that give rise to the duty… yet the duty which is common to all the cases where liability is established must logically be based upon some element common to the cases where it is found to exist.
To seek a complete logical definition of the general principle is probably to go beyond the function of the judge, for the more general the definition the more likely it is to omit essentials or to introduce non-essentials. The attempt was made by Brett M.R. in Heaven v. Pender… As framed, it was demonstrably too wide, though it appears to me, if properly limited, to be capable of affording a valuable practical guide.
At present I content myself with pointing out that in English law there must be, and is, some general conception of relations giving rise to a duty of care, of which the particular cases found in the books are but instances. The liability for negligence, … is no doubt based upon a general public sentiment of moral wrongdoing for which the offender must pay.
But acts or omissions which any moral code would censure cannot in a practical world be treated so as to give a right to every person injured by them to demand relief. In this way rules of law arise which limit the range of complainants and the extent of their remedy.
The rule that you are to love your neighbour becomes in law, you must not injure your neighbour; and the lawyer’s question, Who is my neighbour? receives a restricted reply. You must take reasonable care to avoid acts or omissions which you can reasonably foresee would be likely to injure your neighbour.
Who, then, in law is my neighbour? The answer seems to be – persons who are so closely and directly affected by my act that I ought reasonably to have them in contemplation as being so affected when I am directing my mind to the acts or omissions which are called in question. This appears to me to be the doctrine of Heaven v. Pender…when it is limited by the notion of proximity introduced… in Le Lievre v. Gould…if proximity be not confined to mere physical proximity, but be used, as I think it was intended, to extend to such close and direct relations that the act complained of directly affects a person whom the person alleged to be bound to take care would know would be directly affected by his careless act.
That this is the sense in which nearness of “proximity” was intended…is obvious from [the] illustration in Heaven v. Pender of the application of his doctrine to the sale of goods…
…in the class of case now before the Court I cannot conceive any difficulty to arise. A manufacturer puts up an article of food in a container which he knows will be opened by the actual consumer. There can be no inspection by any purchaser and no reasonable preliminary inspection by the consumer. Negligently, in the course of preparation, he allows the contents to be mixed with poison. …
..I confine myself to articles of common household use, where every one, including the manufacturer, knows that the articles will be used by other persons than the actual ultimate purchaser – namely, by members of his family and his servants, and in some cases his guests. I do not think so in of our jurisprudence as to suppose that its principles are so remote from the ordinary needs of civilized society and the ordinary claims it makes upon its members as to deny a legal remedy where there is so obviously a social wrong.’
The full name of this case is M’Alister (or Donoghue) (Pauper) Appellant; v Stevenson Respondent  A.C. 562.
Edited and paragraphed for ease of reading.