Acceptable Discrimination?

There's been an increase in the number of anti-discrimination bills being released throughout the United States and one thing that is common among all of them is that they are very specific about the types of discrimination that should not be permitted and in what arenas. This, of course, begs the question of what types of discrimination are allowed and where? It seems these types of laws may open the door for various discriminatory actions that were not captured in the original legislation. Are there acceptable types of discrimination?