We may have succeeded in taking down the window signs that used to advertise jobs along with warnings of “no blacks” or “no Irish” but that doesn’t mean the discrimination is gone. Discrimination sometimes still occurs, although the hiring decisions that discriminate are done behind closed doors, rather than advertised in the window. Sometimes the discrimination is still obvious: black employees still find nooses at work, women are still openly groped and propositioned. We have come a long way in the decades of legal reforms to ban workplace discrimination but we still have a long way to go.
There are also some forms of discrimination that are more recently prohibited where the laws are still taking shape and discrimination occurs because there isn’t a clear message on what it acceptable or unacceptable; or at least the message has not sunk into mainstream employment practices. Specifically, these newer prohibitions include disability discrimination and genetic information (such as genetic diseases) discrimination. Both of these areas have been fleshed out since the late eighties but seek to prohibit discrimination for those innate mental and physical qualities that for a long time kept disabled people from equal treatment in the workplace. These more recent prohibitions are the result of hard work by movements to protect civil rights of various groups.
Of course, some forms of discrimination are not illegal, some for reasonable reasons and others because we have yet to recognize the unreasonableness. Employment discrimination laws prohibit discrimination on what are considered innate qualities, such as race, sex, religion and so forth. We will probably never reach a point where we prohibit discrimination on attributes like height or hair color because these tend to produce minimal negative effects in the workplace. However, we may see prohibitions on workplace discrimination in other areas such as transgender rights. There’s even a possibility of someday prohibiting discrimination based on obesity but that is far less likely than a more prominent (and very real) impairment of employment opportunities to transgender individuals.