The cause and effect relationship between law and change is very difficult to identify because the ability of law to produce change isprobabilistic, contingent and sequential because even though some changes can occur, other factors such as the morality and values of society affect the efficacy and time lag of laws in causing change. On certain issues like truth, individual liberty, etc., a shared morality and shared values are essential to unify the society. However, not all values are essential and those should be able to change. To cause change, a law should be supported by the society. Its efficacy in change is limited on moral issues in society. Examples are the ineffectiveness of laws prohibiting adultery, homosexual marriage or sexual abuse. The laws prohibiting many drugs, especially marijuana, have been called the “new prohibition” to underline similarity with laws prohibiting alcohol usage. It seems that laws on important drives are more difficult to apply than those on less compelling drives. Marijuana is seen a source of pleasure for many people therefore control should be imposed only against polluted merchandise. Morris Grinsberg suggests that laws should deal only with acts that can be precisely defined and with external observable acts; and the laws should as far as possible respect privacy.
Thus, laws most likely change external behavior, which are consequently later on followed by changes in attitudes, values and morals. So the range of the “external” is enlarged and sometimes affects personal preferences and tastes. In contrast, William Graham Sumner said that laws can regulate only behavior and not values, morals and attitudes. Examples are laws asserting equality for blacks which were not accepted by whites for many generations. On the other hand, this law that required change in behavior has gradually changed attitudes too. Today, the idea of racial superiority is no longer characteristic of whites. The law can change morality and values under specific conditions. Even though there aren’t enough empirical studies, it is true that the efficacy of law depends on it adaptation to morality and values if it aims change.