The constitution neglects communities by allowing outsiders to exploit local resources and wealth, a forum was told.
"The charter has failed to recognise 'local communities' as the word 'local' has been left out of the constitutional text," said former national human rights commissioner, Angkhana Neelapaijit, at a forum organised by the Assembly of the Poor at Thammasat University on Sunday.
According to Ms Angkhana, the exclusion of local communities from the text means the charter overlooks the need to have a sense of attachment and belonging in governance.
"The organic law on political parties allow 'outsiders' to legally become a representative of a community after they have spent at least three years in those communities," she said.
"But the fact of the matter remains -- these people were not born and raised there. Yet they have the right to utilise local resources and acquire ownership of land."
According to Ms Angkhana, if and when resources in a particular area run out, "outsiders" can just pack up and return to their hometowns, while leaving native residents to pick up the pieces.
"We have seen many examples of this. Such exploitative acts were made possible by our charter," she said.
She said the charter also failed to incorporate input from the public when it was drafted.
"Instead, the charter was drafted according to the opinions of a small circle of people who were almost sure to give the text a nod," the activist said.
Meanwhile, Jon Ungphakorn, director of the Internet for People's Laws Project (iLaw), said the charter is hard to amend as it requires support from the senators loyal to the government.
"As such, a constitutional amendment would have to be strongly justified and backed by the people," he said.
"People must be given a say in how the content of the charter should be altered," said the the group's director at the Bangkok Art and Culture Centre, where iLaw announced the names of finalists in a writing and video-making competition for its "Dream Constitution" project.
Participants -- mostly high school and university students -- put together a list of issues should be amended in the charter.
"These include the role of the military, election of provincial governors, abolition of military conscription and revocation of emergency laws in the far South," according to Mr Jon.