Since you like to Google terms how about checking out some other opinions of polygraphs such as those of the Supreme Court?
In the 1998 Supreme Court case, United States v. Scheffer, the majority stated that "There is simply no consensus that polygraph evidence is reliable" and "Unlike other expert witnesses who testify about factual matters outside the jurors' knowledge, such as the analysis of fingerprints, ballistics, or DNA found at a crime scene, a polygraph expert can supply the jury only with another opinion..."
Also, in 2005 the 11th Circuit Court of Appeals stated that “polygraphy did not enjoy general acceptance from the scientific community”
Numerous studies of polygraph validity have achieved rates of 80-95% for the kinds of tests used with specific issues, such as allegations in criminal cases. Drs. Heinz and Susanne Offe reported 93% accuracy in 2007 when using conventional field methods.
In a 2008 article Drs. Frank Horvath and John Palmatier reported accuracy as high as 91%.
Validity of polygraph remains controversial.
Despite claims of 90-95% reliability, critics charge that rather than a "test", the method amounts to an inherently unstandardizable interrogation technique whose accuracy cannot be established.
A 1997 survey of 421 psychologists estimated the test's average accuracy at about 61%, a little better than chance.
Critics also argue that even given high estimates of the polygraph's accuracy a significant number of subjects (e.g. 10% given a 90% accuracy) will appear to be lying, and would unfairly suffer the consequences of "failing" the polygraph
Several countermeasures designed to pass polygraph tests have been described. Asked how he passed the polygraph test, Ames explained that he sought advice from his Soviet handler and received the simple instruction to: "Get a good night's sleep, and rest, and go into the test rested and relaxed. Be nice to the polygraph examiner, develop a rapport, and be cooperative and try to maintain your calm
Other suggested countermeasures include for the subject to mentally record the control and relevant questions as the examiner reviews them prior to commencing the interrogation. Once the interrogation begins, the subject is then supposed to carefully control their breathing during the relevant questions, and to try to artificially increase their heart rate during the control questions, such as by thinking of something scary or exciting or by pricking themselves with a pointed object concealed somewhere on their body. In this way the results will not show a significant reaction to any of the relevant questions
In 2007, polygraph testimony was admitted by stipulation in 19 states, and was subject to the discretion of the trial judge in federal court
