本文的目的在擴展Ethier的模型以探討一些Ethier未考慮到的因素：第一，我們採用一個二財二要素的Heckscher-Ohlin模型，假設生產函數為可變規模報酬，分析政府在境內取締非法勞工的經濟效果；第二，我們使用Mayer的長、短模型來研究取締政策的長、短期經濟效果；第三，我們應用Cavas的理論來比較長短期效果孰大。本文發現，在探討經濟效果時，產量外部性效果是個重要的因素，透過此效果在某些條件下，可能反而會使國民所得提高，長期所得大於短期所得。 The purpose of this paper is to extend Ethier’s model and to explore some issues not considered in his work. First, we consider a two-by-two Heckscher-Ohlin model in which the production functions are subject to variable returns to scale, and examine the economic effects of internal enforcement on illegal workers. Second, we use Mayer’s model to analyze the long run and short run effects of enforcement policy. Third, we apply Chavas’ work to compare the relationships between long run and short run economic effects. It shows that the external output effects caused by variable returns to scale production functions are crucial in determining income and other economic effects. Under certain circumstances, it may even make income increased and long run income effect greater than its short run effect.