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.
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Anonymous2010-02-20 10:45
>>5
So, if Dayshawn has been convicted six times for liquor store robberies in which he spraypainted a purple frog on the store's wall before he left, the jury shouldn't be told about this pattern of behavior?
>>7
Only even a possibility if this is the only piece of evidence against him. But if there are also fingerprints, security camera footage, DNA, etc., I see no reason not to introduce the pattern of past behavior also.
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Anonymous2010-02-20 13:57
>>8
If you have that much evidence anyway why do you need the purple frog? Of course a detective should use leads like this to speed up search times and reduce expenses, less expense means more practical options available for evidence gathering.
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Anonymous2010-02-20 14:18
The purple frog is circumstantial evidence at best -- it in no way places the defendant at the scene of the crime in lieu of a framejob or a copycat criminal. Guilt must be determined beyond a reasonable doubt, so unless there is significant corroborating evidence to support the frog theory, it shouldn't be admissible.
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Anonymous2010-02-22 13:06
>>10
Some states would allow the purple frog evidence to be admitted as evidence of a so-called signature crime.
But yes, using evidence of prior crimes is dangerous. Past crimes involving dishonesty can be used to attack your character, but only if you testify. They try to put some safeguards in place when it's done, but once a jury has heard that someone has a criminal past, their chances of getting a fair trial on the pending charges drop significantly.