The admonition to practice what you preach should apply most of all in the halls of Congress. If those who write the laws don't have to obey them, ordinary citizens may wonder why they should do so.

Congress has for years exempted itself from the sweep of many laws the rest of us are expected to follow. Such exemptions include employee health and safety laws, wage-and-hour rules, and laws barring federal employees from accepting speaking fees from lobbies with an interest in certain legislation.But nowhere is that double standard more glaring than in Congress' insistence on exempting itself from provisions of civil rights legislation - laws that have profoundly shaped the history of this country for the past 20 years.

But Rep. Lynn Martin wants to change all that. The Illinois Republican has introduced legislation that would bring Congress and its committee staffs under the scope of federal civil rights laws.

To bolster her efforts, she recently took aim at what she sees as examples of sex discrimination in the salaries of congressional staffers. She compiled a report showing vast discrepancies in male and female pay scales. According to her research, 79 percent of those earning $20,000 a year or less were women and that 68 percent of those earning $40,000 or more are men.

Although she avoided saying the survey was evidence of widespread sex discrimination, she noted, "Something is terribly wrong here."

But in many ways, the existence or non-existence of discrimination in Congress is beside the point. It's not necessary to show that Congress actually does discriminate against women or minorities in order to show why it should be required to comply with laws it brings into existence. As a matter of principle, those who make the rules simply must be subject to those rules.

Unfortunately, Congress is not showing itself to be in a hurry to do anything about the issues raised by Martin. Congressional indignation over civil rights issues seems to quickly evaporate when those issues come close to home.

Why does Congress exempt itself from all those laws? It's a question that ought to be asked of every candidate in this election year.