low copy number

[jannyneve]

what does a low copy number dna test mean and is it safe in a court of law,

[Buenchico]

'Low copy number' testing is used when only very small samples of DNA are available. The techniques and results are, theoretically, just as valid as any other type of DNA testing. Problems can arise, however, with contamination of samples from other sources.

In general, this is more likely to result in a guilty person going free rather than an innocent person being convicted of a crime. This is because extraneous DNA which contaminates a sample may make it hard, or impossible, to show that the 'scene of crime' sample being tested comes from a guilty suspect.

On the other hand, an innocent suspect's DNA should not occur in a tested sample unless the laboratory has been grossly negligent in its procedures. (e.g. if the same pipette which had been used to test a cheek swab from the innocent person was later used to test a 'scene of crime' sample, then the innocent person's DNA could show up in the 'scene of crime' sample).

There's a very technical PDF on the subject here:
http://www.denverda.org/legalResource/LCN%20DNA%20Profil ing.pdf

This article is rather easier to read:
http://www.gc.cuny.edu/faculty/folio/spring2005/bloodwor k.htm

Chris

[jake-the-peg]

Not convinced about it being morelikely to acquit a guity suspect!

This from innocenceproject.org :

Brian Kelly was the first person in Scotland to be successfully prosecuted solely on the basis of DNA evidence. The facts were uncomplicated: A woman was raped at night in her Ayrshire home in 1987 by a burglar. In July of that year Kelly, a police officer who lived nearby, voluntarily gave a DNA sample to investigators believing this would eliminate him from the inquiry. Thereafter, the lab reported a match and Kelly was charged with the rape. The victim was unable to identify him as the rapist even though she knew him as a police officer. Kelly nonetheless was convicted in 1989 and sentenced to prison for six years. His parole was delayed until 1993 because he refused to admit his guilt. The Scotsman (Nov 23, 2003) recently disclosed that the conviction may be quashed early this year because two separate studies have concluded that cross contamination of the evidence may have produced a false-positive result.

To answer the actual question I think it's safe providing the highest standards have been observed in the procedures - The risk is the human element!