From the latest Journal of Economic Perspectives

Fair trade coffee is a cup half full, according to Raluca Dragusanu, Daniele Giovannucci, and Nathan Nunn in “The Economics of Fair Trade” (Summer 2014, vol. 28, no. 3, pp. 217–36). We are not persuaded. The authors barely mention the fees imposed upon current and prospective fair trade coffee growers by FLO-CERT, the organization that verifies and certifies fair trade products. By not spelling out the fees, the authors may leave readers with a mistaken impression that the fees are trifling. Elliott (2012) summarizes nicely the latest fee structure. For cooperatives of poor producers, the initial application fee is €525, and fees for the first inspection vary from €1430 to €3470 depending upon a cooperative’s size. While certifications are good for three years, annual fees range from €1170 to €2770 and include interim surveillance of growers’ practices. In short, Fairtrade International requires farmers in low-income countries to pay thousands of dollars in order to participate in a network presumably intended to offer poverty relief to its producer organizations as well as protection from allegedly ruthless local monopsonist coffee buyers, called coyotes. The existence of these large and explicit costs to growers casts some doubt on the relatively optimistic conclusions of this paper. As the authors acknowledge, only a small fraction of coffee grown by fair trade producers is able to be sold as fair trade coffee, but readers should also be clear that applying to join the fair trade network does not guarantee a willing buyer on the other side of the market. As Fridell (2007) notes, newcomers to fair trade production are the least likely to benefit because they cannot compete on an equal footing with established cooperatives in an already saturated market. Fridell cites Martinez (2002), who in turn describes the plight of a certified producer organization that searched for eight years to locate a willing buyer.

There's plenty more here in the whole letter to the JEP.