There are relatively fewer studies on the security-check waiting lines for screening cargo containers using queueing models. In this paper, we address two important measures at a security-check system, which are concerning the security screening effectiveness and the efficiency. The goal of this paper is to provide a modelling framework to understand the economic trade-offs embedded in container-inspection decisions. In order to analyze the policy initiatives, we develop a stylized queueing model with the novel features pertaining to the security checkpoints.