This story has been updated.
The Department of Homeland Security plans to spend a total of $1 billion on a controversial airport security program that, despite being in use for at least seven years, the Government Accountability Office said is unproven in catching security threats.
The Transportation Safety Administration challenged the GAO's report, released today, and said the program, in at least one instance, had stopped explosives from ending up on a plane.
The U.S. government has already spent approximately $750 million on the Screening of Passengers by Technique (SPOT) program, which in part trains airport security officers to look out for "micro-expressions" of travelers that may betray nefarious planning, and plans to add another $254 million to the program in 2012, according to a report published today by the Government Accountability Office's Director of Homeland Security and Justice Issues Stephen Lord. ABC News previously reported critics' concerns with the unproven science behind the SPOT program.
WATCH: S.P.O.T. the Terrorist
According to the GAO report, since DHS started collecting data in 2004, the SPOT program has led to thousands of arrests of travelers suspected of immigration violations, drug possession, false documents and other offenses, but not a single one of the arrests was identified as terror-related. In fiscal year 2010, 50,000 people were singled out by the SPOT program, but only 300 eventually were arrested -- none on terror charges, the GAO said. A previous GAO report found that at least 17 known terrorists traveled through at least 23 U.S. airports in the SPOT program without being detected.
In a hearing today before the House Oversight and Government Reform Subcommittee on National Security, Transportation Security Administration Assistant Administrator John Sammon was asked if the program has ever been successful in thwarting a potential terror attack. Sammon recounted the story of an Orlando man who was spotted because of irregular behavior before he was able to place a bag with explosives on the checked bag conveyor belt.
"So, one?" asked subcommittee member Rep. Blake Farenthold, R-Texas.
But before Sammon could answer, Lord, who was also a witness, interjected and told the subcommittee the Orlando man was actually reported by other travelers and a ticket counter employee and had nothing to do with the SPOT program.
After ABC News reported the exchange, the TSA contacted ABC News to assert Sammon's version of events was correct, as reported by some news outlets.
This year the DHS's Science and Technology Directorate completed a four-year study on SPOT and found that while it was better than random screening at spotting criminality, the directorate's study "was not designed to fully validate whether behavior detection can be used to reliably identify individuals in an airport environment that pose a security risk."
The TSA readily admitted that the SPOT program was implemented "before first determining whether there was a scientifically valid basis" for it, the GAO report said, and the DHS "may be years away from knowing" the answer.
But a spokesman for the TSA told ABC News that the SPOT program was just one in several layers of airport security that have successfully deterred another Sept. 11-style attack and the many arrests resulting from SPOT show that it is an effective tool in detecting deception, whether in criminals or potential terrorists.
Another witness, former director of security at Tel Aviv Ben Gurion International Airport Rafi Ron, defended the use of behavioral observation in security, which is used widely in Israeli airports.
"I think that the investment in behavior observation certainly makes sense," Ron said. "We need to spend more attention on people than just items. Observing behavior is one of the basic tools that can be used at the airport."
Micro-Expressions Are Universal, Psychologist Says
The SPOT program is based in large part on the work of Dr. Paul Ekman, a retired psychology professor at the University of California, who devised a system that identifies facial "micro-expressions" and body movements that are out of the ordinary.
"Micro-expressions, the wonderful thing about them, is they're universal," Dr. Ekman told ABC News in January. "There are seven different emotions and it doesn't matter your language or your culture, if you have one of those emotions it is going to appear in your face and if you're trying to conceal it, it may well leak out in a micro-expression."
Other behavioral science experts said they were skeptical.
"The scientific research shows that it's very hard to detect whether somebody's up to no good just by looking at their behavior," Dr. Maria Hartwig, an assistant professor at John Jay College of Criminal Justice in New York and an expert in the psychology of deception and its detection, said in January.
In its conclusion, the GAO reported suggested the DHS study the viability of the SPOT program further.