We discuss the physical and electrical properties of semiconducting crystals necessary for use in orthogonal strip detectors. We also compute what constraints the properties of existing CdZnTe crystals place on the design of orthogonal strip detectors. First we consider the constraints imposed by uniform material that has limited charge carrier transport properties and resistivity. Next, we consider what effects spatially varying electrical properties (non-uniformities) have on the performance of detectors. Finally, we discuss the properties of CZT crystals available today that we have measured in our laboratory, and what ramifications these measured properties have on the design and construction of orthogonal strip detectors.