What is the consensus on retrospective operation of judgments?
<p>I am working on a project whereby I in a particular section I am required to argue against the possible retrospective operation of a judgment of the Supreme Court of a fictional nation. Since there is no evidence available on whether that court's decision would have a retrospective operation in the facts given to us, I am examining as to whether there is any general principle in favor of or against the retrospective operation of judgments around the world. I found a paper regarding the rules of the US Supreme Court, and I am aware of the principles as far as the retrospective operation of statutes is concerned, but any leads on other important jurisdictions around the world would be appreciated.</p>

<ul>
<li>The Romans had the concept of <a href="https://en.wikipedia.org/wiki/Nulla_poena_sine_lege" rel="nofollow noreferrer">nulla poena sine lege</a>, no punishment without law. This has become part of many legal systems.</li>
<li>You might read up on the <a href="https://en.wikipedia.org/wiki/Nuremberg_trials#Legal_basis" rel="nofollow noreferrer">Nuremberg Trials</a> after WWII. They faced the problem that many (but not all) of the German actions were legal according to German law at the time, yet morally repugnant. There were writings and thoughts about this, which came to the point that the perpetrators should have recognized the manifest injustice of their acts even if the acts were instigated by the government.</li>
<li>Things might look slightly different when it comes to administrative law, e.g. the question if the state can require home owners to apply a <em>new</em> fire safety regulation to their <em>old</em> houses, or a <em>new</em> environmental regulation to their <em>old</em> cars.</li>
</ul>

<h2>Retrospective or retroactive?</h2>
<p>These don’t mean quite the same thing.</p>
<blockquote>
<p>A retroactive statute is one that operates as of a time prior to its enactment. A retrospective statute is one that operates for the future only. It is prospective, but it imposes new results in respect of a past event. A retroactive statute operates backwards. A retrospective statute operates forwards, but it looks backwards in that it attaches new consequences for the future to an event that took place before the statute was enacted.</p>
</blockquote>
<p>An example of a retroactive law is one that criminalises an activity that happened at the time that was not illegal a that time. A retrospective law is one that changes the penalty for a criminal activity that happened in the past but has not yet been prosecuted.</p>
<p>Most jurisdictions are fine with retrospective laws but are wary of, or outright ban, retroactive ones.</p>
<h2>Judgements are never retrospective or retroactive</h2>
<p>This is due to the <a href="https://en.wikipedia.org/wiki/Legal_fiction" rel="nofollow noreferrer">legal fiction</a> that judges find the law, they do not make the law. A precedent setting judgement legally clarifies law that was already “out there”; so, even if this is the first time a court has found a particular activity illegal, it always was illegal its just that no one had ever prosecuted it before.</p>
<p>Of course, there is no practical difference between finding law and making law.</p>
<h2>Statutes and administrative law</h2>
<p>The common law is fine with retrospective statutes but is wary of retroactive ones. It doesn’t like either in actions taken by the executive branch.</p>
<p>Whether the legislature can make retrospective or retroactive laws is usually a Constitutional question. Retrospective laws are AFIK, fine everywhere. In the USA, retroactive (or ex post facto) criminal laws are outright banned. However, in most (all?) other common law jurisdictions they are something that is available to Parliament but it is a power rarely and carefully executed.</p>
<p>In criminal matters, a retroactive law is generally considered to be antithetical to the basic Rule of Law that those subject to the law should be able to know what the law is. A statute that retroactively criminalises previously lawful acts needs to explicitly override this part of the common law.</p>
<p>In civil matters, the courts tend to be more sympathetic because retroactivity does not lead to punishment even if it changes the rights of the parties to a case vis a vis one another.</p>
<p>In administrative law, the power to make retrospective or retroactive rules must be explicitly delegated by the legislature in the law that empowers the executive.</p>

interpretation judgment