The term Ex Post Facto is an old Latin phrase that roughly translates to “after the fact.” In legal terms, Ex Post Facto refers to a law that is unenforceable as to a particular defendant because the law makes the defendant’s non-criminal act a crime only after the defendant has completed the act.

​Note: Ex Post Facto laws are found in the United States Constitution at Article 1, Section 9, Clause 3: “No…ex post facto law shall be passed;” and Article 1, Section 10, Clause 1: “no state shall pass any…ex post fact law.” In addition, similar Ex Post Facto laws may be found in the California Constitution.

​Today, Ex Post Facto refers to a law that does any of the following:

​Makes a non-criminal act or conduct a crime after the defendant’s act or conduct is complete. The Law: A defendant cannot be held criminally liable for conduct which was legal at the time the defendant engaged in the conduct but which was subsequently made illegal.

​Makes punishment for a crime more severe after the crime is complete, or

​Limits a defendant’s defense options that existed prior to the defendant’s criminal act or conduct.

​Makes evidentiary rules more difficult for a defendant to defend his case, or

​Makes evidentiary rules easier for the prosecution to prosecute the defendant after the defendant has committed a crime. The law: A procedure for proving the defendant's guilt cannot be made more lenient to the prosecutor than the procedure that existed at the time the defendant committed the charged offense.

​Ex Post Facto & Conduct Credits: Conduct credits that are awarded for good behavior while in jail, prison, or while on work release, cannot be reduced after the crime is committed without violating Ex Post Facto Laws. For example and hypothetically, if the defendant commits the crime of theft, and the jail sentence for theft may be reduced by up to fifty percent for good behavior while in jail, then the defendant is entitled to that same percentage of good conduct credit (50%) even if the law related to the crime of theft changes to reduce the defendant’s good conduct credits to twenty-five percent.

​Ex Post Facto & Retroactive Laws: Sometime the legislature expressly states that a law applies retroactively. With limited exceptions, when the legislature expresses this intent in the law it should only be allowed to either make the defendant’s punishment less severe, or to make the procedure for finding guilt more restrictive to the prosecutor.

​Ex Post Facto & Statute of Limitations: If the statute of limitations is extended retroactively, and the statute of limitations has not yet expired as it relates to a particular person and his or her alleged criminal conduct, then a change in the law that extends the statute of limitations does not violate Ex Post Fact; on the other hand, if the statute of limitations for criminal conduct has expired as it relates to the circumstances of the accused, then any attempt to extend that statute of limitations violates Ex Post Facto laws (as the timing applies to the accused).

​Ex Post Facto & Monetary Fees: Some monetary fees are considered non-punitive and do not violate Ex Post Facto when those fees are increased after the crime is completed. These can include court security fees, booking fees, probation monitoring fees, and more. On the other hand, some fees are considered punitive in nature and cannot be increased after the fact. For example, if the defendant is criminally charged for the crime of driving under the influence of alcohol or drugs (DUI )that occurred before the penalty fines associated with that crime are increased, then the defendant should pay the DUI related fine that corresponds to the amount of fines that existed when the DUI was committed. With some limitations, fees are generally non-punitive and fines are punitive for purposes of Ex Post Facto Laws.

​Ex Post Facto & Crime Enhancements: It is not a violation of Ex Post Fact to use prior criminal conduct to enhance the penalty of a current criminal charge, even if the enhanced penalty did not exist when the defendant committed the prior criminal conduct. For example, if the legislature creates a new law that allows for a first-offense DUI to enhance the punishment of second-offense DUI, then the fact that the law was created after the defendant’s first DUI offense, does not violate Ex Post Facto. This is true because the prior criminal conduct is not further punished beyond the scope of punishment allowed at the time of the defendant’s criminal conduct, but rather, the subsequent criminal conduct is punished due to the existence of a prior condition.

​Note: It is not necessarily a violation of Ex Post Facto if the form of punishment changes. For example, if a crime was punished by incarceration in the county jail at the time the crime was committed, but the law changed and made that same crime punishable by incarceration in a state prison, then only the form of the punishment has changed and Ex Post Facto laws should not apply. In addition, if only the name or numbering of a crime changes after the defendant has committed a crime, then Ex Post Fact is not violated. For example, in 2018, the crime of oral copulation changed from penal code section 288a to 287. This change in the numbering of oral copulation law should not violate Ex Post Facto.

​Ex Post Facto & Post-Conviction Remedies: Remedies to reduce the negative impact of the defendant’s criminal history may be subsequently reduced or denied without violating Ex Post Facto. This is because the denial of post-conviction remedies that were available at the time of the alleged criminal conduct are not considered punitive. For example, if the clearing of a defendant’s criminal history through an expungement or certificate of rehabilitation was available for a particular crime when the defendant committed the crime, but those post-conviction remedies were subsequently denied after the crime was complete, the defendant cannot argue that the new law violated Ex Post Facto.