Just over 10 years ago, nudge theory was introduced to the world by Cass Sunstein and Richard Thaler. Their radical argument was that the government could preserve the freedom of citizens whilst at the same time helping them make better financial, health and happiness choices. The initial success in the USA and UK led to over 500 nudge units across the globe, including institutions like the World Bank and the UN. However, critics challenge its effectiveness and even the main claim that nudges by the government are freedom-promoting. In this exclusive interview, Cass Sunstein defends the ideology and effectiveness of his theory.