Innocent by perception simply means many things.
Two example could be, Jesus broke the laws by unlawfully causing damage in the temple. (John Chpt.2 v13-16.) Yet it was through innocent perception that caused him to react that way. He saw it as an injustice to God and Love.
If a loved one is ready through illness to leave the pain and return to God, another who painfully helps is seen to be guilty by law yet acts out of innocent perception and Love for another.
Another truth is, a child is always innocent by perception through what the child sees and feels. This will lead to false perceptions of what should be, later in life.