We know with 100% absolute certainty that the wiretapping industry – NSA, GCHQ, FRA, etc – has stopped a total of exactly zero terror plots. We can be certain of this fact, as there have been no trials and no convictions of planning widespread destruction. Planning such a crime is almost as serious a crime as executing it, and while there can be secret evidence in some uncivilized countries, the courts and trials themselves are not secret.