Numerical simulations of the direct shear test have been performed under constant normal stress conditions, using the Discrete Element Method. Results are presented to show how the average shear to normal stress ratio acting on the shear band compares with the force data at the boundaries. From the calculations of the stress tensor inside the shear band the corresponding Mohr's circles are obtained and the principal stress directions identified. The principal directions of stress and strain-rate are shown to be coaxial under steady-state conditions. Using the state of stress and strain in the shear band, the interpretation of direct shear test data is discussed in the context of traditional experimental measurements.