The jurisdictional boundaries of canon law - like medieval political boundaries - were often fuzzy and many jurisdictional frontiers rem ained uncertainly defined throughout the Middle Ages. Medieval church courts claimed, and often exercised, authority over num erous aspects of life that people in m odern secularized societies tend to regard as the business of civil government, rather than of church authorities. In the nineteenth and twentieth centuries, moreover, people who live in what we call ‘the developed nations’ have generally come to accept the notion that some areas of hum an thought and behaviour should be treated as purely private matters, free from supervision or control by public authorities of any kind, civil or ecclesiastical. Thus, religious and political beliefs, as well as most kinds of sexual conduct, in this view, are private concerns that the community should not try to regulate. These affairs are the exclusive business of the individuals involved in them, and should be free from public interference so long as the parties do not invade the autonomy of those who do not share their views or who choose not to participate in their activities. Personal conduct becomes a m atter for public intervention only if it creates problems that affect the rest of society.