Past convictions

I recently learnt that Jurors and Judges are not informed of prior convictions during a trial, I found this rather astonsishing.

Should or should prior convictions be mentioned during a hearing?

In most cases, prior convictions should not be brought up.  They did the crime, they did their time, and the guilt or innocence in the current situation should be based on the present facts, not history.  Bringing up earlier convictions would bias the proceedings towards guilt, regardless of the actual evidence at hand.  "Oh, he committed a crime once, he's obviously guilty again."

If the facts of the prior conviction actually have any bearing on the current case, then it should be brought up as evidence as per normal.  This would apply similarly to bringing up any other past behaviour, illegal or not, to establish (a) ability (b) motive (c) character (d) etc.

That said, the prior convictions should definitely be brought up /after/ the guilt of the relevant parties is decided, so it can be weighed in rendering punishment.  For the most part, a repeat offender shouldn't get off as lightly their second time around.