National Diet Library's latest report reveals that Germany's Federal Parliament electoral system underwent major reform in June 2023, fundamentally changing the seat allocation mechanism. This reform responded to the 2021 general election where actual members reached 736 against the statutory 598 seats.
The previous electoral system used a mixed-member proportional representation, with half the seats determined in single-member districts and overall party seats allocated proportionally to second votes (party list votes). This system generated "overhang seats" for parties winning more constituency seats than their proportional share, and "leveling seats" introduced in 2013 accelerated member increases. The new system increased the statutory membership to 630, abolished overhang and leveling seats, and introduced a "second vote equivalent seat allocation" capping party seats at their second vote proportions.
The new system's key feature is that constituency plurality winners may not become elected members if their party's second votes are insufficient. Specifically, when a state party has more constituency plurality winners than seats allocated by second vote share, those with lower vote percentages are successively excluded from election. The 5% threshold clause preventing parliamentary fragmentation was maintained, but the "basic mandate clause" exceptionally allocating seats to parties winning three or more constituencies was deleted.
The Federal Constitutional Court's July 30, 2024 ruling deemed the seat allocation method itself constitutional but ruled the 5% threshold without mitigation measures like the basic mandate clause exceeds necessity under current legal and practical conditions, thus unconstitutional. The court ordered maintaining the basic mandate clause mechanism as a transitional measure until the threshold clause is amended.
The general election held February 23, 2025 under the new system saw turnout reach 82.5%, the highest since German reunification in 1990. Election results showed the Christian Democratic Union (CDU) returning as the leading party, with the far-right Alternative for Germany (AfD) becoming the second party with 20.8% of votes. The governing Social Democratic Party (SPD) suffered a historic defeat with 16.4%. Under the new system, 23 constituency plurality winners (15 CDU, 4 AfD, etc.) did not become elected members, with six constituencies in Baden-Württemberg seeing plurality winners fail to secure seats.
The National Diet Library analyzes that while the new electoral system achieved its goal of limiting member numbers, situations where constituency plurality winners cannot be elected may foster unfairness among voters, with continued reform discussions expected.