The tension between democracy and the rule of law is a much discussed issue in academia. Yet the special case of direct-democratic institutions and their effect on this relationship has not been examined in detail so far. The tension became even more obvious during the last decade when states with direct-democratic institutions had to face problems over popular initiatives that challenged human or fundamental civil rights – for instance over the same-sex marriage ban in California and the anti-minaret initiative in Switzerland. This chapter begins by analysing this tense relationship theoretically and showing some options for examining it empirically in the future. The theory of democracy and the rule of law will be reviewed and supplemented by a focus on direct democracy. In a second step, the review procedures of direct democracies in Switzerland and the US states will be compared. This discussion can be fruitful not only for the Swiss and US debates on the relationship between direct democracy and the rule of law, but also for other countries planning to introduce or to enhance direct-democratic institutions, such as Germany. The conclusions indicate that direct democracy has to be embedded in a constitutional democracy and that it can be abused in a populist democracy. This theoretical claim should be tested in future research.