Johnny Boy (not his real name) is in trouble - he is charged with assaulting Jimmy Victim, an act witnessed by an unconnected third party - Jacqui Witness. Sounds like a fair cop ... but ...
Does it sound like an even easier decision if you know that Johnny Boy has a dozen previous convictions for violence ? He's done it before ... surely he's more likely than a regular Joe to do it again, right ?
How about if Jimmy Victim has his own previous record that marks him out as a small-time gangster ? Hmmm ... could be Johnny Boy was acting in self-defence and isn't it now possible that Don Jimmy is not telling the truth, the whole truth etc?
How about if Jacqui Witness has numerous alcohol-related convictions and until she was caught recently, she subsidised her income with benefits fraud? Not a reliable witness maybe.
Now put all three pieces of information together - basically a villain hit a villain and we should believe it because an alcoholic convicted fraudstress told us so.
This is where Bad Character applications come in. Before the main hearing, a bench of Magistrates can decide which of these pieces of information about the chequered history of the parties involved can be used in court.
In this particular case here, we allowed the previous violence of the defendant to be mentioned and only the violent previous offences of the victim (actual assaults but not money laundering, threats of violence, fraud and lots of etceteras)
After some debate we didn't allow Jacqui Witness' previous fraud to be mentioned and we didn't have any hesitation in denying the application in regards her alcohol convictions.
Goes against my basic instincts to restrict information in this way though. Surely we can trust the Magistrates trying the case to use the previous history where it seems relevant and to disregard it where it doesn't, rather than having a pre-trial trial with one bench of Magistrates pre-chewing the evidence for another bench ?
Also saves money - hint, hint.