The U.S. Court of Appeals for the District of Columbia yesterday reinstated a lawsuit brought by a group of atheists who challenged the constitutionality of Congress' payments of salaries to chaplains for the House and the Senate.

The court ruled 2 to 1 that, while the Constitution provides that Congress can choose its officers without interference from other branches of government, this does not preclude the courts from deciding constitutional questions that may arise from those actions.

The court sent the case back to the trial judge for a decision on the merits of the claim.

In an opinion written by Judge Ruth Bader Ginsburg, the court rejected the government's argument that the question of payment for chaplains should not be decided by the courts because of the so-called "political question doctrine."

Under that doctrine, hinged on the fundamental principle of the separation of powers, the courts avoid deciding matters that the Constitution reserves for Congress or that would require the court to make a decision on political policy.

Ginsburg, joined in her opinion by Senior Judge David L. Bazelon, said that, while the Constitution says Congress can conduct its business "within the walls of the legislative chambers" without intrusion, the Supreme Court has said that Congress "may not by its rules ignore constitutional restraints or violate fundamental rights."

Legal observers said they thought yesterday's opinion would clear the way for any litigant to challenge the inner workings of Congress, provided that some constitutional challenge is raised.

The decision yesterday came in a case brought by Madalyn Murray O'Hair, her son, Jon Garth Murray, and the Society of Separationists, an atheist group O'Hair founded.

They contend that Congress' payment of chaplains' salaries violates constitutional requirements in the First Amendment that the government remain neutral on religious issues.

The appeals court reversed a decision by U.S. District Court Judge Louis F. Oberdorfer, who dismissed the case last year. The appeals court said first that, as taxpayers, the atheists could get their case into the federal court because they had challenged congressional spending power directly and had raised a specific constitutional issue.

Judge George E. MacKinnon, in a lengthy dissent, disputed the atheists' right to get into the federal court on the basis of what he called the "incidental expenditure" of $80,000 for congressional chaplains.