The forensic science regulator has ruled that this technique is sound, although with recommendations about how samples should be handled to prevent contamination. Low copy DNA is a technique used to get a DNA profile from a small number of cells, recently criticised in the case of the man on trial for the Omagh bomb.
The story is covered in the Guardian and on the BBC.
A Forensic Science Service factsheet about the technique is available from here: http://www.forensic.gov.uk/forensic_t/inside/news/fact_sheets.htm
I can't currently find the forensic science regulator report.