HOUSE RESEARCH
Short Subjects
The Constitution and the Legislature
Judie Zollar
October 2002
Prohibition Against Ex Post Facto Laws
What is an ex post facto law?
The state is expressly prohibited from enacting an ex
post facto law by article I, section 10 of the United
States Constitution and article 1, section 11 of the
Minnesota Constitution. An ex post facto law is one
that (1) applies to events occurring before its
enactment, and (2) disadvantages the person affected
by it. The purpose of this limitation is to ensure that
individuals have fair warning of legislative acts that
could operate to their disadvantage.
An ex post facto law is one that has the purpose or
effect of creating a new crime, increasing the
punishment for an existing crime, depriving a
defendant of a defense available at the time the act
was committed, or otherwise rendering an act
punishable in a different, more disadvantageous
manner than was true under the law at the time it was
committed.
A law is not ex post facto if it merely changes trial
procedures or rules of evidence and operates in only
a limited and unsubstantial manner to the accused’s
disadvantage. In addition, a law is not ex post facto
if it is a civil, regulatory law and is not sufficiently
punitive in purpose or effect to negate the civil label.
How do courts determine whether a law is
punitive?
A law is punitive if the legislature intended to punish
an offender for a past act and the law indeed
functions as punishment. In situations where the
legislature does not state whether a statute is intended
to be punitive or regulatory, the court considers a
number of factors. These factors are whether:
•
the sanction involves an affirmative
disability or restraint,
•
the sanction has historically been regarded
as a punishment,
•
the sanction comes into play only on a
finding of scienter,
•
the sanction’s operation will promote the
traditional aims of punishment—retribution
and deterrence,
•
the behavior