Motorists clearly have a meritorious defense in the underlying Speeding ticket case. It is axiomatic that someone cannot be found responsible of the traffic offense charged, i.e., Speeding in excess of a posted speed limit, if the posted speed limit sign was not lawfully erected. Petition of Sharpe (traffic signals unlawfully maintained).
The phony speed limit sign clearly had the capacity to influence the adjudication. Aoude v. Mobil Oil Corp. It is implausible to suggest that the fact of the phony speed limit sign, if presented to the fact-finder (clerk-magistrate), would not have affected the substantial rights of the parties in the matter. Mt. Ivy Press v. Defonseca.
Indeed, had the fact of the hoax been known, at or after the inception of the underlying lawsuit, the Selectmen would have been unable to sustain their burden of proof as a matter of law, and their claims against any motorist would have been dismissed.