Limitations or exceptions at the state level to ex post facto laws?
<p>There is a local (but nationally recognized) law firm that has <a href="https://www.youtube.com/watch?v=tyEZdapjCb0" rel="nofollow noreferrer">this commercial</a>. The "meat" of the commercial is this:</p>

<blockquote>
  <p>A biker is injured and the law firm goes after the insurance company. Company says it won't pay because of a law that is "on its side". Law firm goes to Madison (WI) and gets the law changed. Law firm recovers $2 million for client.</p>
</blockquote>

<p>Now I was under the impression that you cannot hold somebody liable for events that transpired prior to a law being changed/created (ex post facto). Are there cases as above where an entity (person/business) can be held liable for actions prior to them being enacted in law?</p>

<p>For example if my township passed a statute that says "cutting your grass is a civil offense punishable by up to $X", and then sends me a fine for every year I've lived in the house, I don't think that would be enforceable. </p>

<p><em>I know that there are ex post facto laws in the US that are held such as the "Adam Walsh Child Protection and Safety Act" or the "Domestic Violence Offender Gun Ban" that were retroactive (mostly because they do not impose a punishment). I know that States are prohibited from passing ex post facto laws by <a href="https://en.wikipedia.org/wiki/Article_One_of_the_United_States_Constitution#Section_10:_Limits_on_the_States" rel="nofollow noreferrer">Article 1: Section 10, Clause 1</a>, but I'm specifically asking about the legitimacy of the law offices claim and how it could possibly be true.</em></p>

<p><em>I do not know what law the law firm got changed, they don't mention it even though they state pretty prominently that they were thanked for doing so publicly.</em></p>

<p>The exact law that the law firm had "changed" was really a Wisconson Supreme Court decision it did not agree with, and the lawyers found a state senator who sponsored a bill to change the helmet laws in Wisconsin and their description is available on their website.  <a href="https://www.hupy.com/news/helmet-bill-signed-by-governor-damages-cannot-be-reduced-20090827.cfm" rel="nofollow noreferrer">https://www.hupy.com/news/helmet-bill-signed-by-governor-damages-cannot-be-reduced-20090827.cfm</a> </p>

<p>It sounds like the injured rider scenario is talking about the case that made the lawyer want to change the law. The actual law is not being applied ex post facto, it seems. <a href="https://www.hupy.com/case_results/motorcyclist-receives-50000000-policy-limit.cfm" rel="nofollow noreferrer">https://www.hupy.com/case_results/motorcyclist-receives-50000000-policy-limit.cfm</a></p>

<p><em>Ex Post Facto</em> laws in the sense forbidden by  Article I, Section 10, Clause 1, of the US Federal Constitution are laws making some action <strong>criminal</strong> which was not criminal when committed, or laws increasing the punishment for <strong>crime</strong> which apply to crimes committed before the law was passed. This can include fines, but not civil damages. Laws which are not criminal laws may be changed retroactively in some cases, or if not, it will not be because of  Article I, Section 10, Clause 1. </p>

<p>But in the case cited, it does not appear that the new law is being given retroactive effect, even in a civil case, unless I am misreading the available information.</p>

united-states wisconsin ex-post-facto