MEAs are legally binding International Agreements between three or more state parties based on a common environmental goal. The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layerFor the purposes of this Protocol: 1. "Convention" means the Vienna Convention for the Protection of the. The 20th anniversary celebration of Earth. By 1987, just two years after the hole was discovered, an international treaty was in place that cut the use of CFCs in half. In the extent of their competence.