We present a modified version of Young's interferometer to verify experimentally the four interference laws propounded by Fresnel and Arago. Theoretical analysis is given using the complex algebra and the matrix representation for polarizers, rotators and the electromagnetic field. The advantage of the modified interferometer over other spatial coherence-based interferometers is that it provides ease of use in performing experiments and may assist the understanding of physics in undergraduate laboratories. (Contains 6 footnotes and 4 figures.)