If it's still an active law - of course it will be upheld. The difference between positive law and natural law is that natural law states that humans have certain rights, moral values, and responsibilities that are inherent in human nature. Natural law theory is based on the idea that natural laws are universal concepts and are not based on any culture or customs. Whereas positive law are statutes which have been laid down by a legislature, court, or other human institution and can take whatever form the authors want.
In other words, natural laws, such as remedy offered by lawful money, will never be enacted into positive law because they are 'natural laws' and cannot change for according to whatever the authors want.