The U.N. Environment Assembly (UNEA), a new forum of all nations including environment ministers, business leaders and civil society, will meet in Nairobi from June 23-27 to work on ways to promote greener economic growth.
That drive includes giving environmental laws more teeth.
Many countries sign up for environmental treaties but are often slow to ratify and fail to enforce them in domestic laws, on issues ranging from protecting animals and plants from extinction to outlawing dangerous chemicals or regulating hazardous waste.
The Nairobi talks will include a meeting of chief justices, attorneys general and other legal experts. They will seek ways to improve cooperation, speed up ratification of treaties and try to find models for domestic legislation.
"Illegal activities harming the environment are fast evolving and growing in sophistication," UNEP said in a statement. There was insufficient international coordination to catch crime gangs, from illegal fishing to loggers.
One big drawback is that developed nations often fail to provide promised finance to help poor nations fight everything from toxic waste to illegal logging.
And treaties face big hurdles even after they are negotiated. Last year, for instance, nations agreed a new convention to limit mercury, a heavy metal that can damage the human nervous system and cause liver damage and memory loss.
So far the United States is the only nation to have ratified the pact, which needs 50 ratifications to enter into force.
Successes have included conventions such as the 1987 Montreal Protocol for protecting the ozone layer. Others have struggled, such as the 1997 Kyoto Protocol for curbing greenhouse gas emissions which only entered into force in 2005.
The United Nations will also issue a report on ways to crack down on wildlife crime.