The emergence of Brexit and of President Donald Trump have prompted a significant rethink of federalism, sovereignty, and who should decide notions of community. In both cases, charismatic leaders stoked nationalist resentment and anti-globalist back lash against global, cosmopolitan elites. The implications for federalism, the principle of subsidiary, and law have been enormous. At this same time, in this moment (and in prior moments), subnational governments have advanced progressive agendas, challenging nationalist retrenchment. Examples include the rise of sanctuary cities and climate change cities in the United States; subnational legalization of marijuana and innovation in health care, marriage equality, and civil rights; and threats by Northern Ireland and Scotland to withdraw from the United Kingdom after Brexit. This panel would examine these trends and theorize the implications of this moment for a “new progressive federalism“ (to use Yale Law Heather Gerken‘s phrase).