California is about to allow former felons to serve on juries

I would guess that some felons might make it onto a jury with a felony that was (1) a long time ago, (2) completely unrelated to the felony alleged in the current trial, and (3) generally regarded to be a more minor crime.

But I would guess that few felons will make it onto juries, and the ones that do will endure embarrassing questions during jury selections, in front of a room full of their peers, about their past crimes and whether or not they are now sufficiently honest citizens.

  its common law brethren in the Commonwealth

You mean the one that sent thousands of convicts thousands of miles across the ocean to an inhuman hellhole?

[dead]

Was he guilty?

Once upon a time jury duty was considered a privilege, a way for upstanding citizens to shape their community. Losing that privilege was a social punishment, and a way to ensure justice was aspirational--lenient and harsh according to how the community expected itself to behave and evolve.

The Magna Carta, which secured the right to a jury trial, only concerned the rights of the landed gentry. The jury trial was about the landed class having the right to deliberate on the disputes of its own members. It was copied from the system used for matters pertaining to Church lands and clerical crimes; matters that were required to be settled by other clergy through a parallel court system administered by the Church, whose rights and powers were derived from papal authority.

This notion isn't entirely antiquated today. Some scholars argue that one of the reasons the American criminal justice system has become so harsh on minorities is because juries are usually composed of members who live in separate communities from the accused. Their interests are in tamping down on crime, with little incentive to consider the disruption caused by wrenching away men and women from the labor pool and their families. According to this perspective, we should maybe return to a system where jury pools are called from much smaller geographical districts--literally the neighborhood where the crime occurred.

When share cropping was still a thing in the South, before penal labor became a state enterprise, and even during slavery, juries were often quite lenient toward the working class, including blacks. (Conviction rates were much closer to parity between white and black defendants!) Jury members knew that the accused likely worked for someone else in the community, and owed debts to others; unnecessary punishment[1] of the accused indirectly punished jury members' friends and families. Things worked similarly at the turn of the 19th century in major cities, when ethnic communities were compact and courts weren't centralized downtown. Jail time meant leaving a wife and kids without needed income, creating an immediate burden on the community (e.g. more expenditures from the neighborhood church's coffers).

If juries were again composed of members from the community directly impacted by a crime, then it might still make sense to penalize felons from serving. Juries would once again be more about the community policing itself, as opposed to today where we principally conceive of juries as impartial and fair (in the roulette sense) adjudicators of guilt and gatekeepers of retributive justice. Fortunately, most crime is still local. "Black-on-black" is a catchphrase today, but crime is generally neighbor-on-neighbor everywhere.

[1] Of course, if you were black then "unnecessary" would need to take into account the need to sow fear in the black community. But so long as slavery and share cropping kept blacks tied to the plantations and farms, that was far less common than in later years when they became more mobile.