It’s actually the conclusion of 2 things:
- Double Jeopardy means your cannot try someone twice for the same crime
- A juror cannot be held accountable for a decision they make
If both hold true, then logically, a jury can make a decision against legal precedent, without fear of repercussion - unless they are paid/coerced to come to that conclusion, and the defendant - once cleared by by a jury - cannot be tried again.
This means that legally, a jury can say GTFO to jury instructions set by judges.
If it’s a bug, wow. Almost 250 years, and they can’t fix it?
Also, judges are there to make sure both sides play by the rules.