The effect of overruling a former opinion may also be limited by
the dual character of our government.

The courts of the United States follow the decisions of the State
courts in the determination of matters of State law. If a State
law is held by the courts of the State to have a particular
meaning and effect it will be accorded the same in the federal
courts. But if a federal judgment is for that reason rendered in
a certain form, and there is no appeal, it settles the rights of
the parties to the suit forever, even should the State courts
afterward reverse their former rulings as being
erroneous.[Footnote: 2 Deposit Bank _v._ Frankfort, 191
United States Reports, 499.]

De Tocqueville, in his estimate of the American bar,[Footnote: 3
"Democracy in America," II, Chap. XVI.] speaks of it as devoted
to investigating what has been done rather than what ought to be
done; to the pursuit of precedent rather than of reason.

In a very limited sense this is true. Where codes are wanting,
former judicial decisions must serve in their place. But it
would be a mistake to suppose that it is a large part of the
business of American lawyers to search out precedents for the
guidance of the courts. Most cases, after any facts in dispute
are once settled, depend on the application of the simplest
processes of ordinary reasoning. No aid from the past is needed
for this and none is to be had. It has been well said by an
English judge[Footnote: 1 James, L. J., in 1875, Law Reports, 10
Chancery Appeal Cases, 526.] that the clearer a thing is the more