> other commoners

Ummmm..... the Magna Carta was not about protecting the commoners from the king. It was about protecting the peerage from the king. "Jury of peers" is a jury of other members of the peerage trying a peer. Commoners were not part of the program.

A peer of the defendant?

Because the defendant was a musician in this case.

The standard of "substantial similarity" in copyright law depends not on how an expert would see things, but on how a reasonable average person would see things. Juries are not perfect, but a jury of random people is probably the most qualified way to determine the question "would average people see these two things as substantially the same."

Leonard French—a YouTuber and actual copyright attorney—does a good job covering the legal standards and issues here: https://youtu.be/t-tsw6Z4eHc.

> a jury of random people is probably the most qualified way to determine the question "would average people see these two things as substantially the same."

A jury of random people can be confused and then convinced by lawyers. That's the way they like it, and that's the problem with jury selection - they chose people specifically because they are not knowledgeable.

Whats better? Experts that can be purchased? Elected or appointed judges who owe favors to those who elected or appointed them?

> Whats better? [...lots of straw-men...]

To start: Not removing jurors simply because they're knowledgeable or have critical thinking skills.