Wirat Kalayasiri, a lawyer and former MP from Songkhla, said he would seek endorsements from 20,000 people to take action against advocates of the charter change.
The Constitution Court yesterday ruled that the draft amendment to change Section 190 of the charter was unlawful.
The court said the government and opposition whips agreed that there would be eight more hours to debate the charter amendment but the House speaker cut the debate short and ordered MPs to vote.
The House finally passed the bill and allowed only 15 days for scrutiny in the second reading.
The court said lawmakers should carefully and transparently debate the draft amendment of the Constitution instead of siding with the government without any respect to the minority in the Lower House.
The charter change, if passed into law, will allow the government to enter international agreements without having to seek approval from the national legislative body.
The court said such a change would negatively impact the check-and-balance system and empower the government to sign international agreements without public consent or parliamentary permission.