I think there are lots of people who have a strong belief in justice regardless of their ideology. Being impartial does not mean you have no foreknowledge of the case but means your willing to make a decision based on the evidence alone. Lots of infamous people are tried and convicted even though their case was quite public.

The problem is I believe there will be a much higher possibility of people with a hard political conviction that will attempt to hide that bias just to get on the jury. And they might. People willing to ignore evidence even if God himself came down and testified.