Two manufacturers have joined a Laurel resident in challenging the District of Columbia's total ban on radar detection devices that are designed to permit motorists to escape police speed traps.

Under a 1961 regulation adopted by the old D.C. Board of Commissioners--since superseded by a home-rule government--the mere possession of such equipment is illegal, whether being operated or not. D.C. is alone on the East Coast in invoking such a rule, the plaintiffs said. Virginia, which outlaws the use of "fuzz-buster" devices, has repealed a former prohibition against their possession.

The suit, seeking to declare the restriction "unconstitutional and illegal," was filed in U.S. District Court in Washington by the Electrolert Corp. of Tipp City, Ohio, and Poptronics Electronics Inc. of Baltimore in conjunction with motorist George Sadler of Laurel.

According to the complaint, Sadler was arrested in 1981 in the District for possessing a radar detector "even though he was not using the equipment" at the time.

A frequent traveler in the city, the court complaint declared, Sadler "desires to maintain radar detection equipment, which is legal in . . . Maryland" to provide protection against speeding arrests there and in other states.

The two manufacturers contended that their sales of the equipment to people who live or might drive in the District has been reduced because of the local prohibition against possessing "any device" designed to "detect or counteract police radar." That, Poptronics contended, would also apply to radios that might intercept police communications.

The office of D.C. Corporation Counsel Judith W. Rogers, who must defend the case, reported that "we have seen nothing on that yet." Rogers has a standing policy against commenting on pending cases.