"In the Trans-Pacific Partnership, USTR has endeavored to ensure that all voices are heard in the attempt to find the correct balance of views on complicated and complex trade issues," the agency said in a June statement. "To ensure public input on TPP from the start, USTR solicited written comments from interested individuals, organizations, and businesses before entering into the talks."

The agency has also "sought advice before negotiations began -- and continues to do so as they progress -- from scores of individual advisors" who serve on trade advisory committees in President Barack Obama's administration, the agency said.

Still, critics said they are concerned that the TPP will go beyond tough copyright-enforcement provisions found in ACTA and the U.S. Digital Millennium Copyright Act (DMCA).

The leaked copy of the TPP may require Internet service providers to cut off customers who are accused of repeated copyright infringement, said Carolina Rossini, EFF's director for international intellectual property. That type of rule would create a "private enforcement" regime beyond many countries' current laws, she said.

The treaty could also call for a DMCA-style takedown process for websites hosting user content. Some countries have "better due process" where users can challenge complaints from copyright holders, she said.