<span>In July 1836, Andrew Jackson issued the Specie Circular, which required that public lands be purchased using "gold or silver," since it was thought that this would be better for the US economy. </span>
The hero known as Heracles.
it allow s U.S corporation to move out of the U.S where wages are cheap
The clause is really a state's rights clause. A state may not pass a law that makes something illegal that was legal before the law was passed. In other words if a state suddenly passed a law that said it is no longer legal to park your car in front of any government building, but it was legal to do so yesterday, the police cannot come to your door and issue a ticket for parking in front of a government building because you did it yesterday.
The constitution actually uses the phrase ex post facto law in Article 1 Section 10 Clause 1.