Legal protections for children against sexual exploitation vary among countries. All countries surveyed by the International Catholic Child Bureau have laws protecting children from being sexually abused by an adult, but many of these laws have large loopholes, and the minimum age of consent varies as well. Laws dealing specifically with child pornography generally cover only production and distribution offenses, although some countries, including Canada, Germany, the U.S., the U.K., Norway, Austria, and the Netherlands have also banned the possession of child pornography. At the international level, several legal instruments contain specific provisions outlawing child pornography. Obstacles to effective law enforcement include new technologies that facilitate the dissemination of materials, limited personnel and resources, and the clandestine nature of child pornography.