Brouhle, K., C. Griffiths, and A. Wolverton, 2005: The use of voluntary approaches for environmental policymaking in the US. (ipcc.ch)
The business leaders, clearly addressing the US, which is the now the only and largest emitter of greenhouse gases not to have signed Kyoto or pledged to support a new protocol since the newly elected Australian PM stated he will sign, urge policymakers here to move away from a vague voluntary approach on carbon standards to a mandatory standard. (dotearth.blogs.nytimes.com)
But while CISPA and other bills give the Department of Homeland Security and other agencies more power to monitor problems, they all take voluntary approaches. (scientificamerican.com)