What I said was that those actually making the decision on the basis of the evidence (the Jury) are the best arbiters of the truth at that time. They are the ones who have seen the evidence, been party to the cross examination of the accused, victims, witnesses etc. I didn't say they are always right, but they are in the best position to make the right decision. Certainly better than you or I who have likely one seen snippets of evidence provided through the prism of the media.
Also, don't forget that a jury is 12 people and therefore it is unlikely that the individual biases of one can affect the verdict of all.
They have seen the evidence they are permitted to see.
Due to police cuts, lack of manpower, an incompetent lawyer, mistaken witnesses or experts that are believed, discredited witnesses or experts who should be believed, or numerous other reasons there could be evidence that would create a different truth from the one opposing lawyers are trying to sell them.
Bias is just one factor. Hence, I reserve my judgement abut judicial outcomes. I might have mentioned before that I was involved in a civil case where the defendant was committing perjury in court, and in the middle of his perjured testimony on the stand, asked if he could take a break as he was fasting and it was Ramadan and he had to break his fast with a date and water as it was sunset. That little act may have influenced the judge. Anyway, he won the case as the judge found him more believable.
My husband was a witness for the plaintiff, based on meetings he had with the two parties together at his office (as their accountant) about their informal partnership. One of the claims of the defendant was that no business meetings had ever taken place with my husband and the plaintiff, and that he had never been involved in any informal partnership with the plaintiff.