POWER usually comes with privileges attached. In the executive suite, perks can range from bonuses and cars to corporate jets and country club memberships. In the halls of Congress, privileges have included free banking, airport parking spaces, and even cheap haircuts.But what is acceptable for executives may not always be equally appropriate for politicians. A New York Times/CBS poll shows growing public resentment toward the basic privileges lawmakers enjoy. Three-fifths of respondents called perks such as free mail and travel allowances "unjustifiable." Members of Congress also enjoy another kind of privilege, less well known but perhaps even more troubling: exemption from many laws that govern other Americans. As one example, members of Congress are not subject to laws against sexual harassment. Any congressional employee who wishes to file a complaint can only appeal to a congressional ethics committee. No one can seek recourse in the courts or before executive agencies. This exemption is ironic in the context of the charged Senate hearings on sexual harassment. Similarly, senators and representatives have exempted themselves from laws such as the Civil Rights Restoration Act of 1988, the Age Discrimination Act of 1967 and amendments to it in 1975, and the Equal Employment Opportunity Act of 1972. A double standard of justice - one for those on Capitol Hill, the other for ordinary citizens - bespeaks arrogance toward the very laws Congress believes will serve the public interest. In the absence of any legal recourse on sexual harassment, Sen. Charles Grassley (R) of Iowa plans to introduce legislation allowing congressional employees to sue for discrimination. Charging that exemptions are hypocritical, he also wants lawmakers to include themselves in pending civil rights legislation. At a time when members of Congress are seeking to restore luster to their institution, one obvious duty is to trim special fringe benefits. More important, they must recognize their fundamental responsibilities as well as incidental privileges. The highest ideal of lawmakers should be to obey fully and scrupulously the laws they make.