Polygraph screening examinations have increased dramatically in the past 15 years. This increased usage has produced debate concerning the impact on individual rights to privacy. An argument against polygraphs is questioning the validity and reliability. Research has clearly demonstrated the continued validity and reliability of the polygraph assessment process in spite of spontaneous countermeasures employed by examinees. Individuals subject to polygraph screening examinations for sensitive information access, or employment with some security organizations, have recently become more vocal and organized in their opposition. In addition, the news media tend to highlight only the negative, sensational issues regarding polygraph screening examinations. Early use of the polygraph was related primarily to a small number of personnel, however the larger population pool today and availability of information on the Internet regarding this tool has resulted in more scrutiny regarding the polygraph's validity and reliability. A small group of scientists has raised these issues, claiming that countermeasures can be effective in defeating the polygraph process. Polygraph countermeasures can be defined as any measure employed by an examinee to defeat the examination. There are two basic types of countermeasures addressed on the Internet: behavioral and physical or manipulation of the data being recorded. The validity and reliability of polygraph tests as affected by various medications have had minimal research inquiries. The most commonly prescribed drugs in the country do not influence the results of a polygraph examination. Research has demonstrated the possible impact of countermeasures on the reliability of test results. Modern examiners must adapt to the countermeasure threat present today and improve methods and measures. 10 references