2012 marks the 20th anniversary of the 1992 Earth Summit, held in Rio, which, at least to environmental lawyers, is known for gifting us with the Rio Declaration (27 soft-law principles setting out the basic standards of international environmental law), Agenda 21 (a road map aiming at achieving sustainable development), and the Forest Principles (a non-binding good practice document on forest management). 20 years down the line, 120 heads of state find themselves in Rio once again for the follow-up summit titled the United Nations Conference on Sustainable Development (UNCSD), or Rio+20. The summit will run from June 20-22 (in…