FBI Admits Mistakes in Security Wiretaps

The FBI says it sometimes gets the wrong number when it intercepts conversations in terrorism investigations, an admission critics say underscores a need to revise wiretap provisions in the Patriot Act.

The FBI would not say how often these mistakes happen. And, though any incriminating evidence mistakenly collected is not legally admissible in a criminal case, there is no way of knowing whether it is used to begin an investigation.