Climate Policy in the State Laboratory

The report examines 'vertical diffusion'—the process by which state policies move to the federal level—identifying key drivers such as state champions, spillover effects, and policy learning. It argues that early state action and interstate cooperation can shape federal outcomes, citing the Regional Greenhouse Gas Initiative (RGGI) and California vehicle emissions standards as examples of influential state-led initiatives.

• The most influential drivers of vertical policy diffusion are the advocacy of state champions and the existence of spillover effects. When combined, these two factors can trigger federal adoption even if the policy has not spread widely across other states.
• Early implementation of state policies provides a strategic advantage, as the resulting lessons learned are more likely to inform and shape federal policy than federal policy is to shape state action.
• Policies that achieve wider horizontal diffusion among states are more likely to be adopted federally. Consequently, states are encouraged to design policies that foster interstate cooperation and multi-state collective action, as seen with the California standards and the Regional Greenhouse Gas Initiative (RGGI).
• While business support is helpful during policy development, it is not considered a critical requirement for the vertical diffusion of a policy to the federal level.
• The availability of cost data does not appear to be a significant factor in whether a state policy is adopted federally, potentially because federal policymakers viewed such data as irrelevant or the data was unavailable.

APA

Lash, J. (n.d.). Climate Policy in the State Laboratory. World Resources Institute. https://www.wri.org/research/climate-policy-state-laboratory

Chicago

Lash, Jonathan. Climate Policy in the State Laboratory. World Resources Institute, n.d. https://www.wri.org/research/climate-policy-state-laboratory.

Wikipedia

{{cite report |last1=Lash |first1=Jonathan |title=Climate Policy in the State Laboratory |publisher=World Resources Institute |url=https://www.wri.org/research/climate-policy-state-laboratory |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{lashndclimate, author = {Lash, Jonathan}, title = {{Climate Policy in the State Laboratory}}, institution = {World Resources Institute}, url = {https://www.wri.org/research/climate-policy-state-laboratory}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }