Polygraphs are not admissible as evidence in our courts either. Because they are not 100% accurate.
While the polygraph technique is highly accurate, it is not infallible and errors can occur. According to the American Polygraph Association over 250 studies have been conducted on the accuracy of polygraph testing during the past 25 years. Recent research reveals that the accuracy of the new computerized polygraph stytem is close to 100%. <snip>
http://www.truthorlie.com/accurate.html
Close only counts in hand grenades and horseshoes.
But, if the young lady WOULD submit to one, it would at least give the prosecuter a 99 plus % idea as to wheter or not she's telling the truth or not. (Albeit not admissable as evidence.) But, on the other hand, if she is lying, it cannot be used against her either. So, I see no risk in her submitting to one. (Unless, of couse, she
is lying. But even still, it can't be used against her for prosecution although it could lead to some serious embarassment.) Nobody knows who to believe at this point. Right now, it's 50/50 I suppose. Toss of a coin. A polygraph would tip the scale in my opinion.
I can see if someone who has charges against them refuse a polygraph. Fifth amendment and all. But there aren't any charges against the young lady. She can only gain credibility if she took and passed the exam.