EX POST FACTO LAWS
[Latin, “After-the-fact” laws.] Laws that provide
for the infliction of punishment upon a person for
some prior act that, at the time it was committed,
was not illegal.
Ex post facto laws retroactively change the
RULES OF EVIDENCE in a criminal case, retroac-
tively alter the definition of a crime, retroac-
tively increase the punishment for a criminal
act, or punish conduct that was legal when com-
mitted. They are prohibited by Article I, Section
10, Clause 1, of the U.S. Constitution.An ex post
facto law is considered a hallmark of tyranny
because it deprives people of a sense of what
behavior will or will not be punished and allows
for random punishment at the whim of those in
power.
The prohibition of ex post facto laws was an
imperative in colonial America. The Framers of
the Constitution understood the importance of
such a prohibition, considering the historical
tendency of government leaders to abuse power.
As ALEXANDER HAMILTON observed, “[I]t is easy
for men . . . to be zealous advocates for the rights
of the citizens when they are invaded by others,
and as soon as they have it in their power, to
become the invaders themselves.” The desire to
thwart abuses of power also inspired the
Framers of the Constitution to prohibit bills of
attainder, which are laws that inflict punishment
on named individuals or on easily ascertainable
members of a group without the benefit of a
trial. Both ex post facto laws and bills of attain-
der deprive those subject to them of DUE
PROCESS of law—that is, of notice and an
opportunity to be heard before being deprived
of life, liberty, or property.
The Constitution did not provide a defini-
tion for ex post facto laws, so the courts have
been forced to attach meaning to the concept. In
Calder v. Bull, 3 U.S. (3 Dall.) 386, 1 L. Ed. 648
(1798), the U.S. Supreme Court provided a first
and lasting interpretation of the Ex Post Facto
Clause. The focus of the Calder case was a May
1795 resolution of the Connecticut legislature
that specifically set aside a March 1793 probate
court decree. The resolution allowed the
defeated party in the probate contest a new hear-
ing on the matter of the will. The Court in
Calder ruled that the Connecticut resolution did
not constitute an ex post facto law because it did
not affect a vested property right. In other words,
no one had complete ownership of the property
in the will, so depriving persons of the property
did not violate the ex post facto clause. The
Court went on to list situations that it believed
the clause did address. It opined that an ex post
facto law was one that rendered new or addi-
tional criminal punishment for a prior act or
changed the rules of evidence in a criminal case.
In Calder, the Court’s emphasis on criminal
laws seemed to exclude civil laws from a defini-
tion of ex post facto—that is, it implied that if a
statute did not inflict criminal punishment, it
did not violate the Ex Post Facto Clause. Twelve
years later, the U.S. Supreme Court held that a
civil statute that revoked land grants to pur-
chasers violated the Ex Post Facto Clause
(FLETCHER V. PECK, 10 U.S. (6 Cranch) 87, 3 L.
Ed. 162 [1810]). However, in 1854, faced with
another opportunity to define ex post facto, the
Court retreated from Fletcher and limited the
prohibition to retroactively applied criminal
laws (Carpenter v. Pennsylvania, 58 U.S. (17
How.) 456, 15 L. Ed. 127 [1854]).
In Carpenter, the Court noted that the
esteemed legal theorist SIR WILLIAM BLACK-
STONE (1723–80) had described ex post facto in
criminal terms. According to Blackstone, an ex
post facto law has been created when, “after an
action (indifferent in itself) is committed, the
legislature then for the first time declares it to
have been a crime, and inflicts punishment
upon the person who has committed it.” Using
this as the understanding of ex post facto in
1789, the Court reasoned that it must have been
the Framers’ intent to limit the clause to crimi-
nal laws. However, notes from the Constitu-
tional Convention indicate that the clause
should cover the retroactive application of all
laws, including civil laws. The only exception for
ex post facto laws discussed at the Constitu-
tional Convention was in case of “necessity and
public safety” (Farrand, 1937).
Since the Carpenter ruling, the Supreme
Court has struck down some retroactive civil
laws, but only those intended to have a punitive
