In the 1890 case of Hoff v. Iron Clad Manufacturing Company, the U.S Supreme Court dealt with a dispute over patent rights. The plaintiff, Hoff, claimed that Iron Clad Manufacturing had infringed on his patented design for an improvement in metallic railway-ties (a component used in railroad construction). However, the defendant argued that they were not infringing as their product was based on an expired patent and thus available for public use. The court ruled in favor of Iron Clad Manufacturing Company stating that once a patent expires anyone is free to make or use the invention without paying any royalties to the original inventor. Therefore, if someone improves upon an expired patent and secures a new one for it like Hoff did; he cannot prevent others from using or making products based on original expired patents even though those might be similar to his improved version.

In the dissenting opinion for Hoff v. Iron Clad Manufacturing Company, it was argued that the patent in question should not have been invalidated. The justice believed that while there may be similarities between Hoff's invention and previous patents, this did not necessarily mean his design lacked novelty or inventiveness. He pointed out that many inventions are improvements upon existing designs and can still be considered unique if they offer a new or improved solution to a problem. Furthermore, he disagreed with the majority's interpretation of what constitutes "obviousness," arguing that hindsight bias could make an invention seem more obvious than it actually was at the time of its creation. Thus, he felt that invalidating Hoff's patent based on these grounds was unjustified.