The regional parliament of the German state of Brandenburg voted on Thursday to make political parties put an equal number of men and women up for elections.
The bill, proposed by the Green party and backed by the Social Democrats and the Left which govern the state in a coalition, makes Brandenburg the first German region to set such a gender rule. It comes into force in the second half of 2020.
Women hold just over a third of the seats in the Brandenburg parliament, a shortfall often put down to parties' failure to put enough women candidates forward.
Although Germany has been led by a woman, Chancellor Angela Merkel, for the past 13 years, women are under-represented in politics and business. The share of women in the federal parliament fell from 36.5 percent to 30.8 percent between 2013 and 2017.
Arguably the world's most powerful woman, Merkel has never positioned herself as a campaigning feminist. Gender parity "just seems logical," she told Die Zeit newspaper on Sunday. "That's not something I have to bring up constantly."
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Merkel's conservative Christian Democrats (CDU) and the far-right Alternative for Germany (AfD) voted against the bill.
Norway enacted measures for gender balance in politics decades ago. In 1983, the Norwegian Labour Party imposed a 40 quota for women candidates and was followed by other parties and municipalities. Oslo imposed a similar law for the boards of listed companies in 2008.
Feminist activists said they hoped Brandenburg's decision would serve as an example for other states and the federal parliament.