If there is a "truth serum" that works, it is a secret that nobody is giving up.
The debate earlier this year on interrogation techniques in the war on terrorism raised anew a question that goes back at least 2,000 years. Is there something you can give a person that will make him tell the truth?
The ancient Romans had an answer: Yes.
" In vino veritas"-- "in wine there is truth" -- is sometimes attributed to the natural philosopher Pliny the Elder. The observation made in the 1st century has been borne out over the millennia by many a remorseful inebriate. And, in truth, alcohol given as intravenous ethanol was an early form of truth serum.
In the 21st century, however, the answer appears to be: No. There is no pharmaceutical compound today whose proven effect is the consistent or predictable enhancement of truth-telling.
The modern fascination with truth-eliciting drugs began in 1916 when an obstetrician named Robert House, practicing in a town outside Dallas named Ferris, saw a strange event during a home delivery.
The woman in labor was in a state of "twilight sleep" induced by scopolamine, a compound derived from the henbane plant that blocks the action of the neurotransmitter acetylcholine. House had asked her husband for a scale to weigh the newborn. The man looked for it and returned to the bedroom saying he could not find it, whereupon his wife, still under the anesthetic, told him exactly where it was.
House became convinced that scopolamine could make anyone answer a question truthfully, and he went on to promote its forensic use.
Police departments used it -- and in a few cases judges permitted it -- throughout the 1920s and 1930s. Other drugs were also tried, most famously the barbiturates Pentothal and Amytal. But by the 1950s, most scientists had declared the very notion of truth serums invalid, and most courts had ruled testimony gained through their use inadmissible.
Notorious CIA search
The emerging consensus did not stop the most notorious search for truth serum, the CIA's Project MK-ULTRA. Starting in 1953, the agency tested the behavioral effects of several drugs, including their effects on interrogation. Many people were given substances without their knowledge or consent. Frank Olson jumped from a hotel window to his death after taking the hallucinogen LSD.
The program ended in the late 1960s. Its abuses -- many revealed in congressional hearings in 1977 -- produced bad publicity for the spy agency.
Whether a search for truth serums has occurred in recent decades, and especially since the terrorist attacks of Sept. 11, 2001, is a matter of differing opinion.
Gordon H. Barland was a captain in the U.S. Army Combat Development Command's intelligence agency in the 1960s. Before leaving active duty in 1967 he was asked to write up "materiel objectives." He put on the wish list a drug that would aid interrogation.
He later became a research psychologist and spent 14 years working at the Department of Defense Polygraph Institute. While psychopharmacology was not his specialty, trying to catch liars was.
"I would have expected that if there was some sort of truth drug in general use I would have heard rumors of it. I never did," said Barland, who retired in 2000 and now lives in Utah. He further doubts that the government would again engage in such experiments, given the MK-ULTRA experience.
"It would be very difficult to get a project like that off the ground," he speculated.
Another psychologist who spent 20 years in military research said he also "never heard anything like that or knew of anyone who was doing that work." He spoke on the condition of anonymity because interrogation is not his specialty.
Some doubt the practicality of running, or keeping secret, such a research agenda.
"I can't imagine it," said Tara O'Toole, director of the Center for Biosecurity of the University of Pittsburgh Medical Center.
"We haven't been able as a government to create anthrax vaccine. The idea that we could develop a [truth] drug de novo strikes me as outlandish," she said. "That would be a really major research and development project that would be hard to hide."
For the record, spokesmen for the Army medical research command, the Defense Advanced Research Projects Agency (DARPA) and the CIA say there is no work underway on truth serums.
Whether such a substance could ever be used legally is a question some legal scholars believe is still open.
"In the United States, no law at either the state or national level makes the use of truth serum a crime per se," Jason R. Odeshoo wrote in the Stanford Law Review in 2004.
Information gotten through drug-aided interviews would not be allowed in a trial because of the Constitution's privilege against self-incrimination, but it might be legal to use truth serum "solely for intelligence-gathering purposes," he argued. Similarly, while the Geneva Conventions forbid its use against prisoners of war, if terrorism suspects aren't considered POWs the conventions wouldn't block it, he wrote.
Curiously, truth serum was once viewed as a way of preventing, not promoting, abusive interrogations.
The Prohibition era, which coincided with scopolamine's popularity, produced widespread graft in police departments and district attorneys' offices. Reports of "third-degree" interrogation and forced confessions were common.
"In this climate 'truth serum' was powerfully represented as a sophisticated, scientific, and non-violent alternative to unsavory police methods," wrote Alison Winter in a history of truth serum published in the Bulletin of the History of Medicine in 2005.
A second act?
This ambiguous legal status, combined with advances in neuroscience, lead some to suspect there may be a second act for truth serum.
"There is a large number of neural circuits that we are on the verge of being able to manipulate -- things that govern states like fear, anxiety, terror and depression," said Mark Wheelis, a scientist at the University of California at Davis and a historian of chemical and biological warfare.
"We don't have recipes yet to control them, but the potential is clearly foreseeable," he said. "It would absolutely astonish me if we didn't identify a range of pharmaceuticals that would be of great utility to interrogators."
Recent research with the hormone oxytocin is especially provocative in this regard.
Produced by the brain, oxytocin is best known for stimulating uterine contraction during labor (when it is sometimes given under the trade name Pitocin), and for promoting milk "letdown" during breast feeding. Animal studies have shown it is also important in mate bonding and social attachment.
In a study published last year, Michael Kosfeld and Markus Heinrichs of the University of Zurich set up an experiment examining oxytocin's effects on trust.
About 130 college students were randomly given a snort of oxytocin or placebo. Half were then designated "investors" and were given money. They could keep or transfer some or all of the money to a student "trustee," whom they did not know and could not see.
The act of transferring money tripled its value, creating a big payoff for the trustee receiving it. That person could then keep it all or acknowledge the investor's trust by returning some portion.
The investors getting oxytocin on average transferred more money than those getting placebos, and twice as many -- 45 percent vs. 21 percent -- showed maximal trust and transferred it all. Interestingly, oxytocin had no effect on how much money trustees shared back with their investors, suggesting that the hormone acted specifically to promote trust in situations where there was risk and uncertainty.
Paul J. Zak, a neuroscientist at Claremont Graduate University in California, helped supervise the Swiss experiment. He later went to a meeting called by DARPA and presented the findings. When he was finished, a military scientist asked him: "How do I use this stuff tomorrow?"
Zak said he dodged the question. He observed that classic interrogation techniques, in which one person acts as the "good cop" and creates a bond with the prisoner, probably already makes use of the brain's own oxytocin. He added that, "we are just showing you the neurophysiology behind it."
And that ended the conversation.