My fiance is in prison for manslaughter, after a bad trip on magic mushrooms caused him to hallucinate that his best friend was a terrorist trying to kill him. His public defender and the defence investigator were the only people who showed him and me humanity during the horrific process.

Someone can be "guilty" of something, but not of the crime the prosecution was trying to pin on them. For example, my fiance is undoubtedly guilty of killing his friend. But was he guilty of murder? No. Manslaughter? Yes.

And the fact of being "guilty" - people assume someone "guilty" is necessarily a bad person. In the case of my fiance, he's not a bad person, he's always tried to be a GOOD person, but that particular night, a combination of stupid recklessness (taking the mushrooms) mixed with pre-existing mental illness, led to a horrific outcome that no one could have predicted, and an innocent person is dead and someone who loved them and would never have hurt them in their right mind, is imprisoned for decades.

So yeah, public defenders are so important. Because being "guilty" isn't a binary. Someone can be guilty of "something" but what that is might not be what the prosecution alleges. And being "guilty" and being "evil" are not synonymous, and that's something the general public doesn't understand.