SEATTLE — While some public interest groups took to the streets here last week to protest the policies of the World Trade Organization, others are taking the battle to the courts.

Known as NGOs, or nongovernmental organizations, these groups oppose WTO trade agreements as being harmful to the environment, the food supply and the intellectual property of local communities. They have filed several suits against corporations and government agencies on such issues as the planting and labeling of genetically modified foods and the sale of natural resources.