By Ursula Knapp
KARLSRUHE, Germany (Reuters) -Germany's top court has rejected a change to the electoral system that would have disadvantaged smaller parties in parliamentary elections, although it upheld a reform that would shrink the bloated Bundestag.
A reform law introduced by Chancellor Olaf Scholz's coalition government to abolish an exception to the 5% rule, a threshold parties must reach to enter the German parliament, is partly unconstitutional, Constitutional Court judges found.
The electoral law reform was challenged by the conservative Christian Social Union and the Left party, both of which benefit from that exception and are in opposition.
Germany's electoral system, which allows only parties that win a minimum 5% of the popular vote to take seats in parliament, was drawn up after World War Two to prevent parliamentary fragmentation and the sort of proliferation of minor parties that aided the 1930s rise of Adolf Hitler's Nazis.
Scholz's coalition wanted to abolish the only exception to this rule: parties that come first in at least three single-member constituencies gain parliamentary seats in proportion to their nationwide vote share, even if it is less than 5%.
Removing this exception would damage the equal footing of parties, the top court ruling said, stipulating that it remain in place while the government considers modifications.
The most recent beneficiary of the rule was the Left party, heirs to the former East German Communist Party, which won three directly elected mandates and formed a faction with dozens of legislators, despite receiving just 4.9% of the vote nationwide.
Bavaria's Christian Social Union (CSU), permanently allied to the Christian Democrats (CDU), also benefits. Since it runs only in the southeastern state, it rarely gets over 5%. The CSU remains a parliamentary fixture since it tends to win most of Bavaria's 45 constituencies outright.
"The obvious attempt to eliminate political rivals via the diversions of electoral law has been thwarted," Thorsten Frei, a senior CDU lawmaker, told the RND media group.
However, the top court upheld a tweak in the election law that would shrink the Bundestag - Germany's federal parliament, which has grown to 733 seats in recent years - to 630 in what the three parties in Scholz's coalition claimed as a victory.
Until now, under Germany's unique mix of direct and proportional representation, if a party won more seats via the direct vote than it would get under the party vote, it would keep the extra seats - but more were added for other parties to ensure their proportional vote is reflected accurately.
That will no longer be the case. Under the new law, each party must simply enter the Bundestag with its proportional share of 630 total seats.
(Reporting by Ursula Knapp in Karlsruhe and Thomas Escritt, Rachel More and Sarah Marsh in Berlin; editing by Bernadette Baum and Mark Heinrich)