Paul Fitts' classic work (1954: J Exp Psychol) is a staple for all undergraduate courses in motor control and is a core topic in human factors and systems engineering. Fitts' work has garnered significant interest because it provides a basic and elegant formulation for predicting movement time for goal-directed actions (i.e., Index of Difficulty in bits of information: ID=[log2[2A/W]). Indeed, some researchers have stated that Fitts' work provides a law-based measure of human performance â€“ an assertion quantifying Fitts' Law as the movement sciences "law of relativity". The goal of this symposium is to outline recent work examining fundamental support for, and violations to, Fitts' formulation of speed-accuracy relations. The first talk (Zelaznik) will outline behavioural mechanisms associated with speed-accuracy relations and provide recent evidence that individual differences in speed-accuracy relations are correlated. The second talk (Tremblay) will examine speed-accuracy relations across a range of IDs and outline whether Fitts' theorem provides a unitary or non-unitary basis to predict movement time for amplitude- and width-based manipulation to an aiming environment. The third talk (Heath) will outline speed-accuracy relations related to Fitts' theorem in the oculomotor system. Last, Digby Elliott will serve as Reactor and discuss the relative merits of ascribing Fitts' work as a law-based or conceptual framework in the movement sciences. The ultimate aim of this symposium is to generate debate regarding the relative merits of expressing Fitts' work as a law-based phenomenon in the movement sciences. Supported by NSERC (MH, LT, DE).