If laws are so important why do they constantly change?

Answer 1

Laws change because society changes.

It used to be illegal for blacks and whites to dine in the same restaurant.

It used to be legal to beat your wife with a stick no thicker than your thumb.

Children used to have no rights whatsoever.

As the United States have progressed as a society, in a never ending fight for equality, the laws have changed because of actions of people like Martin Luther King.

Another example is that when gasoline powered vehicles were first sold in mass production, they emitted quite a bit of pollution. When it was realized that this was in fact very harmful to people, plants and animals, the laws changed to help protect ourselves and our environment.

The laws change because context changes. What may have been relevant two hundred years ago no longer is.

Answer 2

Relevance; applicability; fairness.

A law is pointless if the crime is so unlikely to be committed that it wouldn't matter, and/or if it has no bearing on everyday life (what was considered illegal 50 years ago may now be quite acceptable). A law may not be worded in the ay it needs to be so that it does (or does not) apply to the crimes it intends (or doesn't intend) to define and punish. A law must be fair so that it can be acceptable as a part of the justice system; saying only people below a certain income or above a certain age can be guilty of some crimes is very unfair and very injust.