Explain How Roberts, Crane, Spar and La Mure and Levy and Kaplan would explain the failure of the Harkin-Engel Protocol and the negative impact on the companies.

Explain How Roberts (2003), Crane (2001), Spar and La Mure (2003) and Levy and Kaplan (2009) would explain the failure of the Harkin-Engel Protocol and the negative impact on the companies, Nestlé, Cargill, Barry Callebaut, Mars, Olam, Hershey and Mondelēz.