For Lithium, step by step.
The "expert" raising the trousers/dna evidence was challenged by Findlay to explain, clearly and lucidly to the jury, the relevance of the "evidence" just raised.
Amidst much waffling, the expert was forced to concede that the trousers/dna could not, in any way, be linked to the murder, the murder scene, or to draw any assumption, however feeble, of a link between the two.
It was, in fact, the "expert" who broke the rules here, and Findlay who stomped all over it. Finday handled that particularly well - he didn't "feel he had to explain it away" - he demonstrated, quite clearly, that the "expert" was making false claims about the relevance of the DNA sample on the trousers
However, an objection had been raised to that false evidence being heard by the jury, on the basis that it was prejudicial and without foundation, and that objection was over-ruled - the jury heard it anyway, in its full prejudicial form.
The rules of our courts are quite clear - the probative value of any evidence must outweigh its prejudicial effect - didn't happen here.