there Mr. Justice Schofield, the author of the original opinion,
thus disposed of it: "Although in McFarland _v._ People, 72
III., 368, the writer of this opinion expressed the belief that a
similar instruction was free of legal objection, his remarks in
that respect were unnecessary to a determination of the case then
before the court, and they were made without sufficient
consideration, and are manifestly inaccurate. They are now
overruled. The question of competency is one of law, and
therefore for the court; but the question of credibility,--that
is, of worthiness of belief,--and therefore the effect of the
competent evidence of each witness, is one of fact, and for the
jury."] If not, that acquires by this attack a double force.

Chief Justice Bleckley of Georgia once remarked that courts of
last resort lived by correcting the errors of others and adhering
to their own. Nevertheless, they have often, years after
formally announcing a certain legal doctrine in one of their
opinions, declared it to be unsound, and overruled the case in
which it was laid down. They do this, however, with natural and
proper reluctance, and never if this doctrine is one affecting
private rights of property and has been followed for so long a
course of time that it may be considered as a rule on which the
people have relied in exchanging values and transferring titles.

The public, however, have rights to be regarded as fully as
individuals, and if a right of private ownership has been
adjudged to exist, which involves a public loss, the precedent
thus created might be overruled with less hesitation than one
would be determining rights and correlative obligations that were
purely private. Thus the North Carolina courts for seventy years