At least a third of every political party's list candidates must be women in order to qualify for national polls, under a proposal backed Tuesday by constitution drafters to promote gender equality in politics.
In a secret session, the Constitution Drafting Committee (CDC) voted 17 to 13, with two abstentions, to approve the 1-in-3 gender proportion proposal.
Suphatra Nakhaphiew, the CDC's spokeswoman announced the measure after the meeting ended.
Adding a gender element to elections ensures that women have a stronger representation in parliament, she said.
The proposal, entitled "the proportion of opposite genders", requires that each political party define on its party list whether candidates are male or female. This will determine that women are in fact under-represented, said Ms Suphatra.
Only women who were born female will be considered female under the law, as it does not yet include transgender people, she said. This may change in the future, she added. The CDC also voted to have a similar gender proportion applied to local election candidates, but it was rejected, with a 22 to 10 vote with two abstentions.
In contrast to national elections, local elections are dominated by independent candidates rather than parties.
If a gender proportion is imposed, it might put too many limits on candidates, she said.
"This is a new page in history. While past charters mentioned a lack of female representation in parliament, there has never been a gender proportion law such as this one," she said.
Gender equality is also integrated into the charter's budget allocation regulations, said Thawilwadee Bureekul, a CDC member.