Final answer:
The exact number of court cases in which NFIP regulations have been overruled as unconstitutional is not provided. The Supreme Court has invalidated an average of 18 federal laws per decade and has voided an average of 122 state and local laws per decade. Specific cases have resulted in the declaration of unconstitutionality of certain federal laws and regulations.
Step-by-step explanation:
The exact number of court cases in which the National Flood Insurance Program (NFIP) regulations have been overruled as unconstitutional is not specified in the provided information. However, it is important to note that the Supreme Court has invalidated an average of 18 federal laws per decade and has voided an average of 122 state and local laws per decade. Additionally, there have been specific cases where certain federal laws and regulations have been declared unconstitutional, such as National Federation of Independent Business v. Sebelius in 2012.