A lot of people don't realize this, but JCs have never been about determining "guilt" or "innocence".
"Guilt" has already been determined by two "witnesses" coming forward; JCs have always been about determining the accused's state of "repentence".
The confusion comes, I think, from having seen lots of courtroom dramas on TV and in the movies (both on the part of the individual who the JC is being held over and - in some cases - even the elders on the JC).