In addition to setting forth detailed provisions for a compliance mechanism within the terms of an MEA (see discussion of Guideline 14(d)
), Parties to an MEA also can develop a compliance mechanism after the MEA enters into force. There are two general ways that this can happen. First, an MEA can direct and empower the COP to create a compliance mechanism, either through a general mandate or through specific parameters for the mechanism. Second, if the MEA is silent as to means for ensuring compliance, the COP can take subsequent action to develop a compliance mechanism.
At the regional level, the LRTAP and Espoo Conventions in the UNECE region 
provide two examples; while at the international level, two examples of this are provided by (1) the Vienna Convention for the Protection of the Ozone Layer, 1985 (which was subsequently followed by the Montreal Protocol on Substances that Deplete the Ozone Layer (1987) (as amended in London 1990, Copenhagen 1992, Vienna 1995, Montreal 1997 and Beijing, 1999) and (2) the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
The compliance mechanisms described following Guideline 14(d) generally were established after the entry into force of the agreement. However, they were generally established pursuant to specific provisions in the MEAs. In contrast the LRTAP and Espoo compliance mechanisms were developed following entry into force of the respective MEAs.
Compliance mechanisms with authority to render stronger judgments and sanctions can emerge from “softer” mechanisms designed to facilitate implementation.