Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/529bv.pdf
Page Number: 618.0

529US2

Unit: $U52

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

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

543

Opinion of the Court

for felony . . . shall not be witnesses.’ ” 110 U. S., at 587–588.
After the date of the alleged offense, but prior to defendant’s
trial, the last provision (excluding convicted felons from
being witnesses) was repealed.

The defendant argued that the retrospective application of
the felon witness-competency provision violated the Ex Post
Facto Clause. Because of the emphasis the parties (and the
dissent) have placed on Hopt, it is worth quoting at length
this Court’s explanation for why it rejected the defendant’s
argument:

“Statutes which simply enlarge the class of persons who
may be competent to testify in criminal cases are not
ex post facto in their application to prosecutions for
crimes committed prior to their passage; for they do
not attach criminality to any act previously done, and
which was innocent when done; nor aggravate any crime
theretofore committed; nor provide a greater punish-
ment therefor than was prescribed at the time of its
commission; nor do they alter the degree, or lessen the
amount or measure, of the proof which was made neces-
sary to conviction when the crime was committed.

“The crime for which the present defendant was
indicted, the punishment prescribed therefor, and the
quantity or the degree of proof necessary to establish
his guilt, all remained unaffected by the subsequent
statute. Any statutory alteration of the legal rules of
evidence which would authorize conviction upon less
proof, in amount or degree, than was required when
the offence was committed, might, in respect of that
offence, be obnoxious to the constitutional
inhibition
upon ex post facto laws. But alterations which do not
increase the punishment, nor change the ingredients of
the offence or the ultimate facts necessary to establish
guilt, but—leaving untouched the nature of the crime
and the amount or degree of proof essential to convic-
tion—only remove existing restrictions upon the compe-