I don't know how you could replace the jurors but I think they're only as good as the rest of the system. I mean, if they don't get to hear or see certain evidence because it was deemed non-permissible or it was hidden or destroyed, they can't make a good decision. Not to mention at one point we had no DNA evidence. We relied on junk science with bite marks and shoe prints and other things.

Although there are indeed issues with peers (and witnesses). I was in a large lecture hall some time ago and someone came in to do an staged purse snatch. You couldn't see the person's face and they were moving fast.

When the class was shown a lineup to say who it was, most all agreed it was one of the suspects. When asked why, they said he was tall (he was much taller than the others in the lineup).

And that was the whole point. People will try and identify based on little info and they make the incorrect assumption that the lineup they were presented with actually has the real perpetrator!

So if you presented a lineup (maybe an impartial organization other than the police) and made it really clear to the witnesses that the perp may very well NOT be in the lineup, you would probably fix a lot of bad identifications. And you wouldn't have detectives trying to influence a decision. That would be a good start.