Should it not be possible to be convicted of only some of the crimes rather than all or nothing?
Perhaps a fairly sharp curve, since the charges would be mostly linked to each other, but given the 0-200 scale of prosecution vs defence tallies:
easy victory (>20)= Not Guilty on all charges
narrow victory(+10 to +20) = 10% chance of Guilty on each individual charge
nailbiter (-10 to +10) = 50% chance of Guilty on each charge if the jury isn't hung.
serious loss (-10 to -20) = 90% chance
total loss (<-20)= Guilty as charged
Or perhaps add some timing info to the crimes structure, so it is harder to convict you for cold case crimes and you mostly get nailed for the more recent ones unless you do particularly bad?
EG: Instead of a single count of crime instances, have an array of four values (Solid, hot, stale, cold).
Each month, there would be a chance of moving some hot crimes to the stale pile, and each year a chance of moving some stale crimes to the cold case pile.
Each day, some of the hot, the occasional stale, and the rare cold case would be nailed down with evidence and moved to the solid slot. Specific odds would vary depending on police and privacy laws.
A liberalization event of the laws could perhaps move some crimes from solid to hot as the evidence used becomes inadmissible.
When going up for trial, you'd face all the solid cases, and some of the hot ones, and less of the stale and few of the cold.
When deciding guilt, the different cases would get a different modifier on the jury roll, so hot = +10 defence, stale = +20, cold = +30, and you'd be a bit more likely to get off of the charges with less evidence even if you lose the solid cases.
Liberals already in jail could also get hauled up for another court visit if some crimes move to solid because the cold cases investigators got a good roll that month or a prisoner leaks something under torture or just bad judgement depending on the laws.