The Supreme Court criticised the independent experts for deciding that the I sample should not be tested for DNA after finding that their was no trace of cellular material, which basically means that no DNA could be recovered for testing using the techniques available at the time. The judges believed the test should have been carried out anyway and believed that, had this been done, it may have revealed the presence of MK's DNA. Why they believed they knew better than the experts whether or not a test was viable is unclear. Of course, we now know they were wrong in conjecturing that MK's DNA would be found - the DNA now identified in the I sample is from AK so does not confirm the theory that this knife was the murder weapon.
Unbelievably, they then criticised the independent experts for their insistence that Stefanoni should have followed established methods for her testing, stating that "the skill of the operator and his good sense" must also be considered. They went on to say that all DNA analyses since 1986 would be put into question if there was an insistence on following established protocols. If they are right DNA profiling is an art, not a science, and should not be given the respect it currently enjoys in the courts. They are, of course, wrong. DNA profiling is a science. For the operator to produce valid results they must follow established methods.
The prosecution argued that it is not enough for the independent experts to show that the samples had not been handled properly creating the possibility of contamination. According to the prosecution it was necessary for the independent experts to prove exactly how the contamination occurred. I doubt you would find many forensic scientists who agreed with that proposition. But the judges accepted the prosecution argument, stating that the acquittal, "is based on the erroneous belief that the burden of proving the absence of contaminants was on the prosecution". That belief is not in any way erroneous. Indeed, I know that some experts believe an appeal to the ECHR would overturn the Supreme Court's view on this point.
I haven't read the whole of the Supreme Court judgement but the part of it relating to the forensic evidence reads like the worst of our own Appeal Court judgements - a frantic attempt to twist the evidence in order to uphold a guilty verdict rather than admit that the original court got it wrong.