Re: Very interesting...
"I do not understand why a criminal should get an out of jail free card when an investigator doesn't follow the rules."
Let's take that apart. What do you mean by "criminal"?
(a) Somebody who's committed a crime or
(b) Somebody who's been convicted of committing a crime?
If you reply (a) this raises the question of how do you know who they are? Because they've been convicted? So really your only option is (b) unless, of course, it was yourself, then you'd know for certain.
Having established that, let's say you're going about your innocent way (I'm giving you the benefit of the doubt here) when some investigator who can't be arsed with following the rules thinks you might have committed the crime he's investigating and manufactures some evidence against you.
You're duly convicted and, by the standards I hope we've agreed on, you're a (b); a criminal. You know you're innocent but we all have to call you a criminal because you've been convicted.
You appeal about the investigator having made up evidence and your appeal is upheld. What happens to you?
Your statement which I quoted seems to disassociate "criminal" from investigator not following the rules. By that thinking you're still a criminal because you were convicted so you don't get a get out of jail free card.
Do you now see why the strict rules of evidence aren't to protect criminals, they're to protect the innocent.
I should point out that for a considerable chunk of my working life my job was, essentially, one of the investigators. My ongoing dread was the risk of finding myself part of a miscarriage of justice if I were not ultra careful.