An assessment of the validity of the laws of filtration and their applications in filtration studies was made. It shows that the assumptions used in formulating some of the filtration rate expressions are incorrect. Furthermore, the experimentally determined relationship between d(2)t/dV(2) and dV/dt was often found to be inconsistent or disagree with the laws of filtration. While applying the laws of filtration may provide information useful to develop empirical models of filtration performance, the same information can be readily obtained using alternative procedures and similar models may be developed with even greater ease independent of the laws of filtration. (C) 2011 Elsevier B.V. All rights reserved.