As is well known the compound CsCuCl₃ exhibits a Jahn-Teller phase transition at 420K. In order to investigate the nature of the dynamic phase above this temperature, magnetic susceptibility measurements have been carried out around the phase transition point on large single crystals. The transition from a static to dynamic Jahn-Teller effect in the single CuCl₆ octahedra is reflected in a change of the value of the spectroscopic g-factors which can be explained in terms of a vibronic reduction factor (Ham factor). The measurements show a large anisotropy of the hysteresis. This can be explained by assuming a cooperative dynamic Jahn-Teller effect occurring in domains.