The 2004 Japanese Invasive Alien Species Act was enacted to control invasive alien species (IASs) and to prevent damage caused by IASs to ecosystems. The Act defines alien species recognized as or suspected of causing damage to ecosystems, human safety, agriculture, forestry and fisheries. IASs are regulated: raising, planting, keeping or transporting them is prohibited without the express permission of the relevant minister. The Act represents a revolutionary advance for biological conservation in Japan. However, enforcing the Act is problematic; dealing with the European bumblebee required resolving a bitter dilemma between biological conservation and agricultural productivity. The difficulties in the control of alien species in Japan stem from the reliance of the country on imports.