Enfranchising Prisoners

My recent talk in St Andrews addressed the issue of immigrants, but one thing that came up in it was whether criminals ought to be enfranchised. It's interesting to read that the European Court of Human Rights has just ruled that a blanket ban on prisoners voting violates their human rights. Interestingly, it seems that this doesn't prevent some - perhaps even most - being disenfranchised, but a blanket ban is unlawful. Perhaps it would be enough to allow just a few to vote.