If a job advertisement or a public notice says "no women need apply" or "foreigners not allowed," the meaning is clear -- and discriminatory.

Similarly, if people are called insulting names because of their colour or their age or because of some physical or mental disability, we all know that such behaviour is discriminatory and degrading. Acts of this kind are easy to spot and relatively easy to put a stop to.

But discrimination can be much more subtle, and harder to stop. When someone does not get the service they want or the job they think they deserve, there may be a discriminatory reason. What has to be shown is whether a person's race, sex, age, etc., was a factor in the denial of the service or the job, or whether it was done only for other, valid reasons.

Sometimes, the only way to tell whether there is discrimination is by looking at the effects on groups of people. If people who use wheelchairs can't get near the service counter, then it is obvious that they are not being well served. Or if people over 40 are almost never hired for a particular job, we can ask whether there is a good reason for this, or whether it is just someone's prejudice against older workers.

It is easy to see how discrimination harms its victims. People are denied work or promotion simply because they are the "wrong" age or sex, or because of the colour of their skin or where they come from. Whether we like it or not, the equality of opportunity that Canadians believe to be basic to our society is not always available to everyone.