The general theme of this thesis was to determine the modulators of biomechanical tolerance values and to quantify the specific resulting injuries of spinal motion segments exposed to pure shear loading. A porcine model was used for all experimental testing due to its similarity in structure to human specimens. A specially designed jig which isolated shear loading was coupled to an Instron 8511 hydraulic testing machine to test the specimens. Several experiments were performed to specifically examine the effects of loading rate, loading direction and posture on the failure behavior of porcine motion segments. As well, serial destruction of anatomical components was performed prior to a second series of tests which attempted to identify the contributions of each structure during applied shear loading. Biomechanical modelling techniques were used to illustrate possible mechanisms of the load sharing strategies as well as illustrate the mechanism of injury of the structures comprising the motion segment during shear loading. The major findings were that following the removal of the posterior ligaments and the facet joints, the intervertebral disc was found to account for the majority of the shear load resistance under both anterior and posterior loading. The posterior elements were involved in either increasing the stiffness of the entire structure, which was the function of the pars during anterior shear loading, or increasing the deformation to failure of the structure, which was the role of the capsular ligaments and the pars under posterior shear loading. A flexed posture increased the moment arm of the pars which resulted in higher ultimate shear load values as well as a larger deformation at failure. The resulting injuries from mechanical tests were similar to those found in clinical conditions and in in-vitro testing. Anterior shear loading resulted in pars fractures with endplate avulsions occurring at higher loading rates and following the preconditioning cycles. Posterior loading injuries were primarily endplate avulsions with edge fractures and facet face avulsions occurring at higher loading rates and following preconditioning cycles. These data begin to identify the different functioning of the intervertebral disc and the posterior elements under anterior shear loading compared to posterior shear loading. The results of the mechanical tests along with the injuries resulting from the tests suggest that the posterior elements may function to protect the disc from injury, however, more evidence is needed to support this hypothesis.