P. Busch has formulated a particular measurement process in order to show that predictable position measurements are impossible in general. Here we apply his formulation to studying the characteristics of various quantum measurements under the limitations which are imposed by the universal conservation laws and prove some theorems related to Busch's theorem. A simple approximate model measuring momentum is analyzed to investigate the roles of energy and momentum conservation. The results reveal the importance of the role of Galilei's principle of (...) relativity. (shrink)