Secret and direct franchise was introduced only in 1918. Since then, the Members of the Landtag have no longer been elected through electors but at the ballot box by persons entitled to vote. Up to 1939, elections were decided by a simple majority. Shortly before the Second World War and with the threat from outside in mind, a truce was agreed by the feuding parties, resulting in a change to the proportional electoral system. At the same time, a qualifying clause of 18%, aimed at keeping extreme forces out of the Landtag, was included in the electoral law. This qualifying clause was removed by the State Court in 1962 since it had no constitutional basis.
A new qualifying clause of 8% was included in the Constitution in 1973. Initiatives for the removal or lowering of this qualifying clause have not so far been successful. Similarly, other attempts to change the electoral law (e.g., to introduce a majority clause covering both election districts) were rejected by the electorate.