Abstract
We study the phase structure and Hall conductance quantization in weakly coupled multilayer electron systems in the integer quantum Hall regime. We derive an effective field theory and perform a two-loop renormalization group calculation. It is shown that (i) finite interlayer tunnelings (however small) give rise to successive metallic and insulating phases and metal-insulator transitions in the unitary universality class; (ii) the Hall conductivity is not renormalized in the metallic phases in the 3D regime; and (iii) the Hall conductances are quantized in the insulating phases. In the bulk quantum Hall phases, the effective field theory describes the transport on the surface.