Disclosing prior convictions to jury

I’m trying to figure out how I got the idea that during a trial, a defendant’s prior criminal record could never be disclosed to the jury (before sentencing). I now see that it’s not the case in Canada from this article (about a criminally stupid criminal - I feel sorry for his lawyer) and not in the UK either.

It looks like revealing a defendant’s criminal record to the jury only occurs if said information would have relevance in establishing the defendant’s credibility and, in some jurisdictions, only in trials involving certain charges, e.g. child sex crimes. I assume that whether the ‘relevance bar’ has been met in any trial is decided by the judge.

I am curious to know if ‘relevance to the defendant’s credibility’ constitutes the only grounds to override the general rule that prior convictions can not be disclosed to the jury. I assume that different countries will have different criteria as well as having possibly different classes of charges where the rule can be suspended, but, again, I’d be curious to hear more about that, too.

Thanks

In the U.S., credibilty (Fed.R.Evid 609, for example) isn’t the only grounds to introduce prior criminal acts. Rule 403* is also in play. Such evidence “may be admissible” to prove “motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, or lack of accident.”
*again, citing the federal rule, but most states have something along the same lines.

On “Law & Order”, the two lawyers argue in front of the judge privately about the advantages and disadvantages of telling the jury, and then the judge rules whether it’s admissible or not.

Another common reason to reveal prior convictions, or charges, (again, L&O) is to establish a pattern. Whether it’s his first or 10th trial for murder/child molestation/theft, justice demands you prove the charges with the evidence regarding that particular crime, not by “rounding up the usual suspects”. Just because someone did it 5 times, does not go toward proving he did it this time. However, it comes up in L&O that if he pattern is the same - he gets them drunk, tails them home, breaks in a window, and ties them up, steals their jewelry - if he did it this way 10 times before and the same facts happened this time - then the pattern is relevant.

It’s not clear how distinctive the pattern has to be, I guess that’s up to the judge, but simply “he broke the same law” is not enough of a pattern.

In the UK it can happen under certain conditions

Witnesses can also have their criminal pasts revealed in court.