The Electronic Frontier Foundation (EFF) has sued the Office of the US Trade Representative (USTR) over information it is withholding on the Anti-Counterfeiting Trade Agreement (ACTA).
The ACTA proposals would dramatically increase the powers of businesses and governments to curtail copyright infringement.
"ACTA raises serious concerns for citizens' civil liberties and privacy rights," said EFF international policy director Gwen Hinze.
"This treaty could potentially change the way your computer is searched at the border, or spark new invasive monitoring from your ISP.
"People need to see the full text of ACTA now, so that they can evaluate its impact on their lives and express that opinion to their political leaders. Instead, the USTR is keeping us in the dark while talks go on behind closed doors."
Other proposals in the treaty include forcing ISPs to hand over subscriber details without providing any evidence of wrongdoing, and dramatically increasing the fines levied on those who breach the law.
The ACTA proposals were discussed at the last round of G8 talks, and the final details are still being formulated. However, they would entail a major rewrite of national intellectual property laws.
The US, Canada, the European Community, Switzerland, Japan, the Republic of Korea, Singapore, Australia, New Zealand, Mexico, Jordan, Morocco and the United Arab Emirates are currently negotiating agreements.
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