Pro and con arguments
Polygraph testing is widely used with convicted sex offenders in the United States to assist in their treatment and supervision, and in 2007 legislation was passed in England enabling a national trial of mandatory testing in the probation service.
In next month's issue of Legal and Criminological Psychology, a British journal, a forensic psychiatrist and a forensic psychologist debate the pros and cons of this approach:
Don Grubin, MD of Newcastle University in the UK endorses the use of polygraphy to monitor whether sex offenders are adhering to their treatment plans. Polygraphy, he argues, is an effective method for "getting a complete sexual history, checking compliance with treatment and supervision and gaining information about an individual's offending."
Gershon Ben-Shakhar, Ph.D. of Hebrew University of Jerusalem objects: "Polygraph examinations have no value as a scientific method for detecting deception and uncovering information the examinee does not wish to disclose."
The full arguments are in September's special issue on human rights in forensic practice; a press release from the British Psychological Society (the journal's publisher) is here. Unfortunately, although I have linked you to the abstracts, you have to pay or subscribe to a journal service to get the entire articles.