considering I’m not a law person, I can’t say any certain thing about this. I think there can be good reasons that juries can’t know the past of accused person.
I think there are people that don’t want their past to be known and we should respect them about this. For example, there are too many bad people that slander random, innocent people for money and stuff. And accused person can do nothing but defend themselves. And that when defending our not enough, advocates could need some information about accused person’s past to say that to juries. But when accused person is not guilty but their life is in trouble and they have to tell about their past it can be unfair for them.
But I, personally, think that they should always check their past right before setting them free. Yes, it can be unfair sometimes but it can be so fair too. For not being in a dilemma, we can do this more fairly. Like, we can do it by the level of crime. People shouldn’t take risks in such things.
Additionally, maybe deciding by their past can have negative effects. Some people believe that people can change. And they say that, “just because they did it in their past doesn’t mean they will do it in the future”. Yes, it can be right sometimes, but not always.
In conclusion, checking their past is always a good idea. I personally don’t think that people can easily change. I would not be that fair and also it’s kind of dramatic way to decide. As I already said, taking risks in this is too dangerous.