Answer by taking a quote from the following article:

Roberto Mangabeira Unger (; born 24 March 1947) is a philosopher and politician. He has developed his views and positions across many fields, including social, political, and economic theory. In legal theory, he is best known by his work in the 1970s and 80s while at Harvard Law School as part of the Critical Legal Studies movement, which is held to have helped disrupt the methodological consensus in American law schools. His political activity helped the transition to democracy in Brazil in the aftermath of the military regime, and culminated with his appointment as Brazil's Minister of Strategic Affairs in 2007 and again in 2015.

The beginning of Unger's academic career began with the books Knowledge and Politics and Law in Modern Society, published in 1975 and 1976 respectively. These works led to the co-founding of Critical Legal Studies (CLS) with Duncan Kennedy and Morton Horwitz. The movement stirred up controversy in legal schools across America as it challenged standard legal scholarship and made radical proposals for legal education. By the early 1980s, the CLS movement touched off a heated internal debate at Harvard, pitting the CLS scholars against the older, more traditional scholars.  Throughout much of the 1980s, Unger worked on his magnum opus, Politics: A Work In Constructive Social Theory, a three volume work that assessed classical social theory and developed a political, social, and economic alternative. The series is based on the premise of society as an artifact, and rejects the necessity of certain institutional arrangements. Published in 1987, Politics was foremost a critique of contemporary social theory and politics; it developed a theory of structural and ideological change, and gave an alternative account of world history. By first attacking the idea that there is a necessary progression from one set of institutional arrangements to another, e.g. feudalism to capitalism, it then built an anti-necessitarian theory of social change, theorizing the transition from one set of institutional arrangements to another.  Unger devoted much of the following decades to further elaborating on the insights developed in Politics by working out the political and social alternatives. What Should Legal Analysis Become? (Verso, 1996) developed tools to reimagine the organization of social life. Democracy Realized: The Progressive Alternative (Verso, 1998) and What Should the Left Propose? (Verso, 2005) put forth alternative institutional proposals.

Which school did he attended?
legal schools across America