  The Bondi-van der Burg-Metzner-Sachs (BMS) group is the asymptotic symmetry
group of asymptotically flat spacetime. It is infinite dimensional and entails
an infinite number of conservation laws. According to the black hole membrane
paradigm, null infinity (in asymptotically flat spacetime) and black hole event
horizons behave like fluid membranes. The fluid dynamics of the membrane is
governed by an infinite set of symmetries and conservation laws. Our main
result is to point out that the infinite set of symmetries and conserved
charges of the BMS group and the membrane paradigm are the same. This
relationship has several consequences. First, it sheds light on the physical
interpretation of BMS conservation laws. Second, it generalizes the BMS
conservation laws to arbitrary subregions of arbitrary null surfaces. Third, it
clarifies the identification of the superrotation subgroup of the BMS group. We
briefly comment on the black hole information problem.
