In order to stop ...the dangerous innovations that finally ruined Athens, no one would have the power to propose new laws according to his fancy; this right belongs exclusively to the magistrates.
Gist of Idea
In a direct democracy, only the leaders should be able to propose new laws
Jean-Jacques Rousseau (Discourse on the Origin of Inequality , Intro letter)
Aristotle says (somewhere!) that control of the agenda for meetings is the key issue in democracies. I assume any citizen can propose a law, but only a magistrate can put it on the agenda. Maybe a separate 'citizen's committee' could filter suggestions.
Rousseau,Jean-Jacques: 'The Basic Political Writings', ed/tr. Cress,Donald A. [Hackett 1987], p.28