BALTIMORE, NOV. 3 -- A judge refused today to throw out federal conspiracy charges against Maryland politicians Clarence and Michael Mitchell, ruling that the question of whether they "corruptly" schemed to block a congressional investigation by their uncle should go to the jury.

Sidestepping the murky rules surrounding congressional lobbying, U.S. District Judge Norman P. Ramsey denied a motion for acquittal in the week-old trial, brushing aside defense contentions that there had been no evidence the Mitchells intended anything more than traditional lobbying when they agreed to help the scandal-ridden Wedtech Corp. of New York stop the investigation in 1984 and 1985.

The House Small Business Committee, headed by then-Rep. Parren J. Mitchell, questioned the eligibility of Wedtech to participate in lucrative no-bid military contracts set aside for minority small business firms.

Clarence M. Mitchell III, a former Maryland state senator, and his brother, state Sen. Michael B. Mitchell, are being tried on charges of conspiring to "corruptly endeavor" to block the probe by Parren Mitchell, their uncle, in exchange for $60,000 from Wedtech. They also are charged with trying to instigate a separate investigation against a Wedtech competitor for an additional $50,000.

Defense attorney Sean Connelly argued today, however, that prosecutors have "proved no bribes . . . coercion . . . blackmail . . . or perjury, promised or othewise," by the Mitchells. Wedtech officials testified variously, he said, to getting the investigation "stopped," "killed" or "squashed," but no witness has said the Mitchells would do so by illegal means.

Prosecutors, Connelly said, have tied their case to the Mitchell brothers' "special relationship" with Parren Mitchell. But lobbying of congressmen historically has been "all about special relationships."

"Who knows what a special relationship is?" asked defense attorney John D. McDermott. "Is it somebody you play golf with, somebody you go fishing with on weekends? Or is it a relative?"

Prosecutor Gary P. Jordan countered that the Mitchells repeatedly gave Wedtech assurances that they could stop the investigation and took advantage of their "familial relationship" with Parren Mitchell.