The Arlington County Board last night postponed awarding development rights for a proposed multimillion-dollar complex around the county's Courthouse Station Metro stop after citizens complained that they had been given too little time to study different plans under consideration.

A special selection panel appointed by the board had recommended approval of the Charles E. Smith Co.'s proposal to build a $150 million plaza on six acres of county-owned land behind the courthouse. The Smith Co., which proposes to develop the plaza in a partnership with the Artery Organization, was one of three finalists selected by the panel. The other two are the Cavalier Development Co. and the Court House Plaza Development Group.

The development is expected to help shape Arlington's future by establishing what has been called a standard of excellence for construction around stops on the county's two Metro lines.

But, following a three-hour public hearing on the subject last night, the board decided to defer action until Dec. 13.

Although earlier the Smith proposal appeared to have backing from a majority of the five-member board, which of the three finalist firms will get to develop the site was unclear last night. The board will first award a tentative contract, then negotiate with the firm selected on such issues as whether the county's land could be purchased or leased and what possible concessions the county may have to make.

In agreeing to postpone a decision last night, the board asked that the Arlington Civic Federation, an umbrella organization for various civic groups, review the selection panel's basis for recommending the Smith Co. Until last night, that information had not been made public.

"We're concerned over the lack of information on the benefits and the drawbacks" of the Smith plan, said Alexander Keyes, a federation member. Kenneth Ingram, federation vice-president, added, "This is a peculiar process we're following in this case. But I think we, the citizens, would like to satisfy ourselves that the proposal the selection panel came up with was best."

Board members Walter L. Frankland and John G. Milliken, who were both on the selection panel, failed to get the board to agree to their respective selections last night. Frankland said he favored the Smith Co. proposal, while Milliken said he leaned toward the Court House Plaza Development group's cresent-shaped plan. Board chairman Stephen H. Detwiler said he tended to favor Cavalier's plan.

Neither board members Dorothy T. Grotos nor Ellen M. Bozman indicated which firm they preferred.

Grotos, noting the citizens' complaints that the selection panel's meetings were closed, remarked, "the citizens seem to feel there is a missing link, that they were left out of this process in the later stages because the meetings were closed."

Frankland contended that there had been significant citizen involvement in the early stages of the planning, especially in arriving at the development goals the county is requiring the developer to meet, such as civic space, minimum number of residential units and maximum office space and the need for retail space.