What Exactly is a Polygraph Test?

In tv shows and movies, polygraphs (or “lie detector tests”) are often painted as mechanisms by which a defendant “gets off” or proves his or her innocence. Polygraphs are machines that hook up to a person to measure their physiological indicators such as perspiration and heart rate.  It was once thought that when a person tells a lie, their heart rate and blood pressure change to indicate so.  However, what many people do not know, is that polygraph tests are generally unreliable (ie. there are “false positives” or negatives), and their use has decreased.  For example, if a person is nervous simply by virtue of taking a lie detector test, their heart rate will increase regardless and their test results will be inconclusive, rather than “passing.”  Polygraphs may also be fooled if one is just able to control their physiological responses.

Rules on Polygraphs

Earlier this Week, the California Supreme Court decided unanimously that blanket, statewide bans on where sex offenders may not live (“Jessica’s Law”) violate the constitutional rights of parolees in San Diego County.  Jessica’s Law (aka Proposition 83), named after a 9-year-old girl who fell victim to a sex offender who failed to report his whereabouts, was proposed via a ballot initiative in 2006.  Due to Megan’s Law, those who have been convicted of a sex crime must register with their local law enforcement agency.

Jessica’s Law therefore barred registered sex offenders from living within 2,000 feet of a school or park where children gather, regardless of whether the crimes actually involved children.  Sex offenders subsequently challenged the law in court, claiming that it made it impossible for them to find a place to live.  The court recognized that the law made over 97% of rental housing in San Diego unavailable, and ruled that the consequences of the law were so severe, it hampered rehabilitation and caused homelessness.  Although the unanimous ruling immediately affects only San Diego County, it will certainly pave the way for the same policies in major metropolitan areas, including San Francisco.

What to Do If You Are Charged With a Sex Crime

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