This is Separation of Power Issue and not a clear cut issue. The principle is that Law, Law-making, and executive-power should be separated.

It's really who you trust more: courts or the people.

1. French law recognizes that French people are not trusted to weigh in the conviction properly, and the court sentences put limits to how can and can't run.

2. On the other hand, corrupting of the courts would prevent correcting the system by voting. If the courts are corrupt all hope is lost.