Gringo, it would be a sad indictment if it had to come down to a choice between the guilty walking free and the innocent being imprisoned.
Unfortunately, this is the case though, Jane. The ultimate consequence of fabricating evidence is jailing the innocent and there is a long list that demonstrates the case.
I fail to understand how we can possibly "know" someone to be guilty if we don't have evidence against them. If evidence needs to "introduced" to prove the charges then by definition it cannot be "known" that the suspect is guilty. You need actual evidence to make that decision.
Nobody likes to see guilty people walk free but it is a greater stain to jail the innocent especially if that is achieved through corruption, no matter how noble the cause is thought to be.