TWENTY HOUSE members joined Rep. Lynn Martin (R-Ill.) last week in sponsoring legislation to fight employment discrimination on the Hill. The proposal grew from a study, "Women in American Society," published by the House Wednesday Group, an organization of moderate and liberal Republican legislators. Democrats are among the cosponsors. Rep. Patricia Schroeder (D- Colo.), who has offered similar legislation since 1978, is expected to reintroduce her bill soon.

There is need for legislation because of the grating fact that our major civil rights laws -- and some labor and worker protection laws as well -- do not apply to Congress or to the federal courts. Lawmakers and judges are not under the same obligation as private employers, state and local governments and the executive branch to hire employees without regard to race, religion, national origin, sex, age and handicap. As a result, Reps. Martin and Schroeder allege, there is widespread discrimination on the Hill where most of the service workers are black and the professional workers white, and where women, on average, earn far less than men.

Those who would reform present practices, however, face two difficulties. A legislator must be free to hire aides who share his political beliefs and special concern for his home district. A new law must allow some exceptions for staff who work closely with a member on political and legislative matters, and Rep. Martin's bill does this. Then, the method of enforcement must preserve the separation of powers so that courts do not have extensive power over legislators and lawmakers are not coercing judges.

House and Senate rules already prohibit employment discrimination, but the only way an employee can enforce rights is by complaint to the ethics committees. Both the Martin and the Schroeder bill would put teeth into these rules by creating outside panels to hear complaints. Rep. Martin would use retired U.S. Court of Appeals judges -- chosen by congressional leaders -- who would hear employment cases and determine what relief to grant. Rep. Schroeder would create a review board with members drawn from the private sector who would report their recommendations back to the House.

It comes as no surprise that this is not the most popular issue before Congress. But those who have taken it on, on behalf of 30,000 legislative branch employees and 17,000 workers in the judiciary, deserve support.