US lawmakers worried over behaviour detection prog expansion

A group of influential lawmakers have expressed concern over the expansion of a "behavior detection programme" of the US government at airports, calling it an "intrusion into the privacy" of the flying public and "not scientific".
As part of the Screening of Passengers by Observation Techniques (SPOT) programme of the Transportation Security Administration (TSA), Behavior Detection Officers (BDOs) carry out screening of passengers, under which they are subject to screening and secondary screening based on their behavior.
Now, under the expanded programme, passengers who refuse to answer intrusive questions posed by BDOs at airport security checkpoints will undergo secondary screening.

"This [Targeted Conversation Proof of Concept] represents an intrusion into the privacy of the flying public through a process TSA has not scientifically validated," four top US lawmakers wrote in a letter to the TSA Administrator, John S Pistole.
While over USD 1 billion has been spent on SPOT, zero terrorists have been identified, apprehended, referred to law enforcement or prevented from boarding an aircraft as a result of the programme.
Its opponents argue that known or suspected terrorists have passed through screening on 23 different occasions in airports where BDOs were present.
TSA has not provided any scientific validation for the programme.

In 2013, the Government Accountability Office (GAO) recommended Congress consider whether to continue to fund SPOT after TSA disagreed with the recommendation that it limit future funding of the programme.