Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/529bv.pdf
Page Number: 608

529US2

Unit: $U52

[09-26-01 10:36:40] PAGES PGT: OPIN

Cite as: 529 U. S. 513 (2000)

533

Opinion of the Court

to meet the burden of proof is simply another way of achiev-
ing the same end.22 All of these legislative changes, in a
sense, are mirror images of one another.
In each instance,
the government refuses, after the fact, to play by its own
rules, altering them in a way that is advantageous only to
the State, to facilitate an easier conviction. There is plainly
a fundamental fairness interest, even apart from any claim
of reliance or notice, in having the government abide by the
rules of law it establishes to govern the circumstances under
which it can deprive a person of his or her liberty or life.23
Indeed, Fenwick’s case is itself an illustration of this prin-
ciple. Fenwick could claim no credible reliance interest in
the two-witness statute, as he could not possibly have known
that only two of his fellow conspirators would be able to
testify as to his guilt, nor that he would be successful in
bribing one of them to leave the country. Nevertheless,
Parliament had enacted the two-witness law, and there was

22 Lowering the burden of persuasion, to be sure, is not precisely the
same thing as lowering (as a matter of law) the amount of evidence neces-
sary to meet that burden. But it does not follow, as the dissent appears
to think, that only the former subverts the presumption of innocence.
Post, at 560–561 (opinion of Ginsburg, J.).

23 We do not mean to say that every rule that has an effect on whether
a defendant can be convicted implicates the Ex Post Facto Clause. Ordi-
nary rules of evidence, for example, do not violate the Clause. See infra,
at 543–547. Rules of that nature are ordinarily evenhanded, in the sense
that they may beneﬁt either the State or the defendant in any given case.
More crucially, such rules, by simply permitting evidence to be admitted
at trial, do not at all subvert the presumption of innocence, because they
do not concern whether the admissible evidence is sufﬁcient to overcome
the presumption. Therefore, to the extent one may consider changes to
such laws as “unfair” or “unjust,” they do not implicate the same kind
of unfairness implicated by changes in rules setting forth a sufﬁciency of
the evidence standard. Moreover, while the principle of unfairness helps
explain and shape the Clause’s scope, it is not a doctrine unto itself, invali-
dating laws under the Ex Post Facto Clause by its own force. Cf. W. S.
Kirkpatrick & Co. v. Environmental Tectonics Corp., Int’l, 493 U. S. 400,
409 (1990).