Not all ex post facto laws are illegal

The 1987 Constitution of the Philippines categorically prohibits the passing of any ex post facto law. Article III (Bill of Rights), Section 22 specifically states: "No ex post facto law or bill of attainder shall be enacted."

According to a Wikipedia page, the term "ex post facto"is a corrupted form of the Latin phrase "ex postfacto" which literally means "out of the aftermath."In a strict sense, an ex post facto law is a law that retroactively changes the legal consequences (or status) of actions that were committed, or relationships that existed, before the enactment of the law. However, in the Philippines, this legal term has been given an absolutely negative connotation because of the above-cited constitutional prohibition.

In our legal system, an ex post facto law is one which:

[1] Makes criminal an act done before the passage of the law and which was innocent when done, and punishes such an act;

[2] Aggravates a crime, or makes it greater than it was, when committed;

[3] Changes the punishment and inflicts a greater punishment than the law annexed to the crime when com­mitted;

[4] Alters the legal rules of evidence, and authorizes conviction upon less or different testimony than the law required at the time of the commission of the offense;

[5] Assuming to regulate civil rights and remedies only, in effect imposes penalty or deprivation of a right for something which when done was lawful; and

[6] Deprives a person accused of a crime of some lawful protection to which he has become entitled, such as the protection of a former con­viction or acquittal, or a procla­mation of amnesty.

Conversely, a form of ex post facto law commonly called an amnesty law may decriminalize certain acts. Alternatively, rather than redefining the relevant acts as non-criminal, it may simply prohibit prosecution; or it may enact that there is to be no punishment, but leave the underlying conviction technically unaltered. A pardon has a similar effect, in a specific case instead of a class of cases though a pardon more often leaves the conviction itself – the finding of guilt – unaltered, and occasionally pardons are refused for this reason.

Ex post facto laws per se are not wrong or unconstitutional especially if it is beneficial. "Ex post facto" means "happening or promulgated after the fact." If vested rights or obligations of contracts are not impaired, and if favorable to the accused, they are okay.

In Hernan v. Sandiganbayan, the Supreme Court was faced with a novel situation wherein the judgment convicting the accused was already final and executory and yet the penalty imposed thereon was later reduced by virtue of the passage of a law. Because of this, not only must petitioner's sentence be modified respecting the settled rule on the retroactive effectivity of laws, the sentencing being favorable to the accused, she may even apply for probation, as long as she does not possess any ground for disqualification, in view of recent legislation on probation, or R.A. No. 10707 entitled An Act Amending Presidential Decree No. 968, otherwise known as the "Probation Law of 1976," As Amended, allowing an accused to apply for probation in the event that she is sentenced to serve a maximum term of imprisonment of not more than six (6) years when a judgment of conviction imposing a non-probationable penalty is appealed or reviewed, and such judgment is modified through the imposition of a probationable penalty.

As a matter of justice which must regulate all elements of a criminal action, the accused must be given the benefit of the provisions of a new law when more favorable to him and, unless there should be final and conclusive judgment at the time, and in matters of prescription when less severe, the new law should be applied. The same principle applies when the modifications introduced by the law refer to the prescription of the penalty, because in its substance the prescription of the penalty is equivalent to the prescription of the criminal action. (G.R. No. L-18260)

Other legal changes may alleviate possible punishments (for example by replacing the death sentence with lifelong imprisonment) retroactively. Such legal changes are also known by the Latin term in mitius.

The discussion above is based on an outline in "Ex post facto law". From Wikipedia, the free encyclopedia.