During the annual meeting of the Committee on Food Labeling of the United Nations Codex Alimentarius Commission (Rome)—which sets standards for the world trade of food products—held this spring in Ottawa, Canada, the US and Argentine delegations blocked efforts to develop a consensus position on whether or how to label foods derived from genetically engineered organisms. The reason for the impasse is that the US and Argentine delegations are calling for "voluntary" labeling, while most other delegates, including representatives of European Union states, Canada, Australia, and Japan, favor some form of mandatory labeling. The difference of opinion is that the US and Argentina argue that genetic modification is not a significant change, and therefore does not require labeling. In response to the current impasse, the committee established a 30-member working group to develop definitions and alternate proposals for such labeling, to be considered at the next meeting, scheduled for May 2000. In the meantime, the US will not be labeling produce from genetically modified sources, and other countries can adopt their own rules. Although the US delegates recommended that the Codex committee direct attention to develop principles for avoiding the "misleading labeling" of foods, including claims of health benefits that are "not based on sound science," committee members deferred discussion of that proposal as "new business."