alt Hacker NewsThis is kind of true. What is unusual about the Post Office is that they have exceptional investigatory powers but anyone can bring a prosecution in the UK.
And it is an important freedom. If the state is declining to prosecute its own, citizens should be able to.
In my view the biggest problem is the credulity of the courts, who are inclined to believe evidence from corporate officers by default, and often refuse efforts to challenge it. The late Ross Anderson documented many cases from the 1990s onwards of people being convicted on bullshit technical evidence.
Maybe the CPS would have seen through it if they had conducted the prosecutions, but I don't think that's obviously true.
It's a negligible freedom. The CPS can always choose to seize control of any prosecution and, if it sees fit, discontinue the prosecution. So at most they can choose to ignore a prosecution unless either the prosecutor or accused bring it to their attention specifically, and if that happens they're obliged to actually do something (though that might be explicitly taking no action, it's distinct from ignorance because there's a process they have to follow by law to decide what to do).
This is an important defence - every Post Office defendant could have chosen (or rather, their lawyers knowing the law could have done so) to flag their case for this process and force the CPS to decide what to do and as you say it's conceivable that in the most egregious cases that would have stopped it †
There are definitely flaws in this system, I just have more confidence in it than I do for the American system. I didn't know Ross Anderson was dead. He did some really good work.
† We know it wouldn't have always worked because there are Horizon casees where the CPS are the listed prosecutor. Jurors weren't the only people who gullibly accepted that the Computer is infallible, but at least the CPS were not employees of the executives who knew this was bullshit and have largely escaped any consequences.