When writers on jurisprudence assert that custom is a source of law their primary meaning seems to be that in any given case a course of conduct persisted in by all or most of the members of a society engenders a rule of law enjoining the continuance of that course of conduct. This, for example, appears to be the burden of Dr. C. K. Allen's discussion of custom in his Law in the Making. He sums up the operation of custom in this sphere by saying that "the thing done" (semble, by all or most members of the community) becomes "the thing which must be done" (i.e., the rule binding on all members of the community ). Now, Dr. Allen progresses straight from the introductory remarks whose purport is thus summarised to a statement of the generally accepted fact that the Common Law of England is, at least in part, a customary law. The clear inference is that wherever in the Year Books or the reports we find a decision based on custom, whether local or general, that custom is applied as a binding rule of law whose content and whose force are both derived from a constant uniformity of conduct in the community or locality.
E. K. Braybroolte,,
CUSTOM AS A SOURCE OF ENGLISH LAW,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol50/iss1/4