The laws of a country or a particular system changes with time, leadership and education, but the laws of any religion doesn't change with time. It remains eternal and the secrets of the art open up only to those who seek sincerely. Black magic is one of them. The logic behind Black Magic is simple - if prayers can heal people, curse can make people suffer. If positive thinking can bring positive changes in thyself and others then negative thinking does bring negative changes in self and others.