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polygraph test is a thing of the past

A few days ago, there were reports saying that investigators wanted Chen Che-nan (陳哲男) to take a polygraph, or lie detector, test, but Chen refused. Chen is the former Presidential Office deputy secretary-general who is accused of involvement in the illegal profiteering racket between the Kaohsiung Rapid Transit Corp (KRTC) and a brokerage firm hiring Thai laborers.

Chinese Nationalist Party (KMT) Legislator Chiu Yi (邱毅) also asked former premier and former Kaohsiung mayor Frank Hsieh (謝長廷) to undergo a polygraph test together with Chen, but Hsieh also refused.

When Vice President Annette Lu (呂秀蓮) sued The Journalist magazine for a story it published in November 2000, the lawyer for the defendants asked Lu to take a polygraph test, but she likewise refused.

Chang Chung-te (張仲德) and Chen Hung-hsien (陳鴻仙), both linked to the killing of former Taoyuan County commissioner Liu Pang-yu (劉邦友) and seven others were given polygraph tests -- as were Kuo Chin-hsing (郭進興) and Cheng Pai-sheng (鄭百勝), who were both involved in a baseball-related gambling scandal. Investigators also ordered the police to give Chang Hsi-ming (張錫銘), a notorious serial kidnapper and gangster, a polygraph test.

It is regrettable that the police often use polygraph tests as an important tool in their investigations, and that the public has such high expectations of such tests. As a result, the polygraph is being abused and more than a thousand people in Taiwan are tested each year.

Taking a polygraph test is scary for both guilty and innocent people. Even worse, given test personnel's frequent lack of professional training and certification, the accuracy of these tests is questionable.

A polygraph or a biofeedback system does indeed provide objective biological evidence that helps determine an individual's psychological state, but the relationships between different physiological indicators are complex.

Even biological reactions that are part of the sympathetic nervous system -- such as skin conductance, skin temperature, heart rate, blood pressure and breathing rate -- may differ in a single individual, even when given the same stimulation. For example, the same stimulus or question may show a clear reaction in skin conductance, while heart rate remains unaffected.

Conducting a polygraph test is time-consuming: there are pre-test preparations, a pre-test interview, the actual test, a post-test interview, and the creation of a polygraph chart. All of these are analyzed. Polygraph tests thus require specialized knowledge and are not as simple as people generally think.

A polygraph test is the modern equivalent of the past practice of beating a confession out of a suspect. There is no difference between physically or psychologically beating some one in order to extort a confession. US courts have adopted the Frye standard as a means of excluding evidence, and they do not treat polygraph tests as admissible evidence.

The US Congress later made a decision to prohibit sales of polygraph machines to police authorities overseas, only allowing sales to educational or research institutions. One wonders how Taiwan's police administration went about importing their machines.

From a legal standpoint, using polygraph tests to get access to an individual's biological or psychological information violates human rights and invades the privacy of the tested person. Developed countries now try not to use polygraphs.

According to a 2003 amendment to the Code of Criminal Procedure (刑事訴訟法), police records concerning a defendant can only be regarded as hearsay evidence, while prosecutorial evidence is the main evidence. Polygraph test results can thus not be used as evidence, which is to be commended. Article 95 of the code stipulates that an accused has the right to remain silent and thus has the right to refuse a polygraph test.

Although police authorities emphasize the high accuracy of polygraph tests, the concern is not with their accuracy, but rather the protection of human rights including the right to privacy. Poligraphs are an attavistic reminent of a bygone era when these rights were routinely ignored.

Chen Han-chiang is a former president of National Hsinchu University of Education and a former New Party legislator.

Translated by Lin Ya-ti
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