Expert evidence cited at the inquiry yesterday has effectively discredited the scientific basis of forensic tests in 1972 which the late Lord Widgery relied on to link five of the Bloody Sunday victims with exposure to firearms.
Mr Christopher Clarke QC quoted extensively from a report commissioned by the Saville tribunal from Dr John Lloyd, an expert on forensic analysis.
Dr Lloyd examined the tests applied to the hands and clothing of Bloody Sunday victims by Dr John Martin, then a principal scientific officer at the department of industrial and forensic science in Northern Ireland.
Counsel pointed out that Dr Lloyd's report contained "some stringent criticism" of the process of reasoning by which Dr Martin, and hence Lord Widgery, reached their conclusions, and as to the validity of those conclusions.
Dr Lloyd challenged the validity of the tests carried out for lead particles, and of the conclusions drawn from those tests. He said that results reached in the absence of control samples - for example, from the hands of those making the test - were scientifically unacceptable.
He also commented in his report that it was "extraordinary" that it could ever be accepted "that the presence on the hand of a single microscopic particle - virtually dust-sized - of a common substance such as lead was significant evidence of firearms residue, and accepted as a positive finding if more than three particles were present on the clothing . . ."
Mr Clarke noted that Dr Lloyd had listed a large number of innocent sources and routes of lead contamination. Mr Clarke commented that if Dr Clarke's expert opinion was well-founded, then "evidence of lead particles upon the hands of the deceased provides no foundation for establishing, much less `piling up', any case against them."