You can legally discriminate ("to make a disctinction in favor of or against a person on the basis of the group or class to which the person belongs, rather than according to merit"), as long as it is not done to a person of a "protected" class.
I believe "sexual orientation" may be a "protected class" these days. If you are white, male, fat, conservative, or a smoker ... you're screwed.
The creation of a "protected class" is the very definition of fascism. Scary, isn't it?