Should human rights be enforced by law or optional?

Nowadays, human rights don't exist everywhere, or they aren't respected all over the world. Should there be a law saying taht human rights must be respected?

The point is that law exists to protect people and pleople have those human rights. It's necessary to enforce human rights by law, because there must be something, somre kind of model to help us against society. 

However, it's not an easy task to do. For instance, not all countries are provided with all the economic resources necessary to give a good education. What's more, religion can also change and influence the law and people: a muslin won't defend the same human rights than a catholic. In addition, there are alse political reasons that make people have a different point of view of all human rights. 

In conclusion, a lot of variety of cultures and religions makes impossible to enforce all human rights in a law, but there should exist different laws for different groups of societies.