On another note, here's a very specific ....
From the U.S. Government's EEO
site:
"The groups protected from the employment discrimination by law. These groups include men and women on the basis of sex; any group which shares a common race, religion, color, or national origin; people over 40; and people with physical or mental handicaps. Every U.S. citizen is a member of some protected class, and is entitled to the benefits of EEO law. However, the EEO laws were passed to correct a history of unfavorable treatment of women and minority group members. "
What may be confusing you, Cais, is the fact that several states have passed laws that make sexual orientation a protected class. The Federal Government, however, has not. The argument is that the things that are considered Federally "protected classes" involve physical characteristics that are so readily apparent that you can be judged on them immediately. In order to know for sure that someone is gay, you have to be told. You can't just tell by looking at them.