Nugatory means to have no ability to enforce something. A law that is created in a state that has a conflicting law, the new law is nugatory and apt to be removed.
When new laws are created and if they are in contradiction to other preexisting laws, they are found to be nugatory and unenforced. Also, very old laws that have been on the statute books for decades that bear no relevance to contemporary life are also considered nugatory.