What happens when the law changes?
<p>Assume a criminal offence occurred in the past (for example 2015), before a new law was passed at a future date (for example 2016).</p>
<p>What law would be referred to by the judge when it comes to sentencing the offender? I think there is a legal term for this in Latin but I cannot find it.</p>
<p>My question is focusing on the United States and the United Kingdom.</p>
<p>I have done some research, and it appears that ex de facto law is not allowed in the United Kingdom to follow directions given by the European Union. However, I am not sure if this covers my question, as it is for actions that were previously legal, whereas my question is about actions that were illegal and then had changes made to them.</p>

<p><a href="/questions/tagged/united-states" class="post-tag" title="show questions tagged &#39;united-states&#39;" aria-label="show questions tagged &#39;united-states&#39;" rel="tag" aria-labelledby="united-states-container">united-states</a></p>
<p>An <em>ex post facto</em> law criminalizes conduct after the fact that was legal at the time, something that is prohibited under U.S. constitutional law. But, as the question states:</p>
<blockquote>
<p>my question is about actions that were illegal and then had changes
made to them.</p>
</blockquote>
<p>If something is a crime in 2015 and this criminal law is violated, and the conduct is then legalized in 2016, the conduct committed while it was a crime does not cease to be punishable as a crime and may be punished criminally.</p>
<p>Often a judge would consider the fact that the conduct was later legalized when evaluating the seriousness of the crime at a post-legalization sentencing, but a judge is not required to do so.</p>
<p>A significant number of pardons and commutations of criminal sentences by Presidents and Governors in the U.S. involve people convicted of crimes for conduct that is now legal or is now punished less severely. But pardons and commutations are purely discretionary.</p>
<p>As an aside, France has constitutional protections that give newly lenient treatment of crimes retroactive effect, but the United States does not.</p>

united-states united-kingdom criminal-law common-law