ONE OF THE time-honored principles of home-rule protection in the District of Columbia is the old Dirty Linen Rule. Local government officials should not go running to Congress for help in settling intramural policy disputes with other local officials. But the other day D.C. Council Chairman David Clarke broke the code. Angry that Mayor Barry had not sought council assistance in planning a new prison for the city, he sought aid, comfort and clout from the chairman of the Senate Appropriations subcommittee on the District. Fortunately, Sen. Arlen Specter of Pennsylvania didn't comply. Instead, he dismissed Mr. Clarke's appeal with the stern notation that he didn't have time to "referee" squabbles between the city's top elected officials.

Mr. Clarke, undaunted, kept on asking the senator to intervene in the prison-planning dispute. The senator tried several times to cut off the chairman, saying, "Mr. Clarke, if you don't like what the mayor is doing, why don't you submit your own plan? Why don't you go your own route? . . . I have had as much of this as I am going to listen to."

If Mr. Clarke does submit a plan for a new prison in Washington, it would be his first. All along, the council's only contribution to the prison-site planning has been a suggestion that the Lorton facilities in Fairfax County be expanded. That ducks the issue; the money and land offer that Sen. Specter was good enough to pursue in Congress was intended for a facility in the District, and Mayor Barry has publicly supported that effort. If Mr. Clarke wants to continue differing with the mayor, that's his privilege. But the squabble is a local one that belongs, if anywhere, downtown, not in the halls of Congress.