The Legal Theory Bookworm recommends Power to the People: Constitutionalism in the Age of Populism by Mark Tushnet & Bojan Bugaric. Here is a description:
Self-described populist leaders around the world are dismantling their nation's constitutions. This has led to a widespread view that populism as such is inconsistent with constitutionalism. This book proposes that some forms of populism are inconsistent with constitutionalism, while others aren't. Context and detail matter.
Power to the People offers a thin definition of constitutionalism that people from the progressive left to the conservative right should be able to agree on even if they would supplement the thin definition withn other more partisan ideas. This is followed by a similarly basic definition of populism. Comparing the two, this book argues that one facet of populism -its suspicion of institutions that are strongly entrenched against change by political majorities-is sometimes inconsistent with constitutionalism'sbthinly understood definition.
The book provides a series of case studies, some organized by nation, others by topic, to identify, more precisely, when and how populist programs are inconsistent with constitutionalism-and, importantly, when and how they are not. Concluding with a discussion of the possibilities for a deeper, populist democracy, the book examines recent challenges to the idea that democracy is a good form of government by exploring possibilities for new, albeit revisable, institutions that can determine and implement a majority's views without always threatening constitutionalism.
And from the reviews:
"Power to the People makes a compelling case for a more nuanced understanding of the relationship between populism and constitutionalism. The book is a useful corrective to work (including my own) that treats norm-breaking and constitutional hardball tactics as inherently problematic for liberal democracy." ―Steven Levitsky, Harvard University
"This book provides a much-needed and refreshing perspective on populism and its relation to constitutionalism, avoiding the common mistake of casually dismissing or demonising populism, and seeking instead to shine a light on the vast array of populist programmes." ―Michael Wilkinson, London School of Economics and Political Science
"This book is so far the most promising comparative constitutional attempt to reconcile the complex relationship between populism and constitutionalism, without generalization." ―Gabor Halmai, European University Institute
"Disaggregating constitutionalism and populism, this magnificent study leaves behind the hasty diagnosis and prediction of others, bringing conceptual lucidity and comparative learning to renewed debate." ―Samuel Moyn, Yale University
"Power to the People helps readers think about today's constitutional troubles. It has become commonplace for scholars to blame 'populism' for the rise of authoritarian and ethno-nationalist leaders and parties. But not every effort to empower ordinary citizens and unsettle entrenched elites is a step toward tyranny. Tushnet and Bugaric provide us with the tools and case studies to begin understanding the differences between changes that promote democracy and those that imperil it." ―William E. Forbath, The University of Texas at Austin, School of Law
"Challenging conventional political and scholarly wisdom, Mark Tushnet and Bojan Bugaric make a powerful case that populism is the solution to rather than the cause of contemporary democratic ills. Power to the People details how authoritarians masquerading as populists are perverting an authentic form of democratic politics, and that the numerous populist reforms championed by the populist left throughout the globe are at least if not substantially more democratic than the contemporary constitutional status quo. Much handwringing on the crisis of constitutional democracy will need substantial reconsideration in light of this major work." ―Mark Graber, University of Maryland, Francis King Carey School of Law