What are the impacts of mandatory GMO labeling?

Genetically modified (GM) food products and their labeling have become a major policy issue with impassioned public debates. We explore the impact of different labeling regimes on consumer attitudes towards GM products and consumer welfare. Our experimental results illustrate that these consumer attitudes do not follow the Uniform distribution as has often been assumed in the literature but instead fit an adjusted Kumaraswamy distribution. If a Uniform distribution is assumed, the advantage of mandatory labeling would be exaggerated. Using an adjusted Kumaraswamy distribution our simulation results demonstrate that voluntary labeling is superior to mandatory labeling with the higher separation cost, while mandatory labeling is not necessarily better with lower separation cost. Therefore, the governments of China and other countries with similar consumer characteristics should consider voluntary labeling for GM food while encouraging innovations that reduce the price of GM food as well as controlling the opportunistic behavior of its producers so as to enhance the advantage of voluntary labeling

That's from a paper just published Li Zhao, Haiying Gua, Chengyan Yue, and David Ahlstrom in the journal Food Policy