Keep educating anyone who might ever serve on a jury about jury nullification https://en.wikipedia.org/wiki/Jury_nullification and make then feel ok about using it aggressively. If people used this every time it looked like the 'justice' system was extorting defendants the practice would stop pretty fast.

If I understand right, this was roughly the system 50-60 years ago. From memory, the average murder trial took under 2 weeks, and very few went to appeal.

We've replaced that with a system which in some ways has much higher standards. There appear to be decades worth of appeals possible on death row, involving all kinds of experts. But the flip side of this is that most trials don't happen, thanks to plea bargains.