[wonderwonder]

They should not be, but historically and continuing into this day, there are some areas including entire states where there is a clear bias against minorities. This means the defendant is potentially at a disadvantage before the first prosecutor has spoken. Placing a minority on the jury of a minority defendant does not guarantee an acquittal in anyway but it does help to mitigate any ingrained bias the jury may have.

In addition, we are supposed to be judged by a jury of our peers. Considering minorities make up ~40% of the population I don't think its a stretch to say at least 20+% of the jurors should be a minority.

The bar to convict should be high and this helps to ensure that. Rather 10 guilty men go free than one innocent man go to jail.