Washington — Can the World Court help resolve the case of Korean Air Lines Flight 7? The Soviet Union, which shot down the plane, is saying ''nyet'' to claim after claim filed by the 13 nations that had citizens aboard the aircraft. Now some United States lawmakers think it is time to sue.
Congress strengthened those who want to drag the Soviets into court when it declared unanimously in a joint resolution that the Soviet attack on Flight 7 was a ''crime'' and ''criminal destruction.''
''The US Senate has never in its history declared another nation to be guilty of a crime,'' thundered Sen. Daniel Patrick Moynihan (D) of New York. ''This is not a small event. There has not ever before been such an event. The charge of crime under international law is a solemn one.''
The next logical step, Senator Moynihan told the Senate, will be for President Reagan to take legal action, possibly by appealing to the International Court of Justice (the World Court) at The Hague.
Over the weekend, legal advisers at the US State Department were trying to decide:
* What international laws may have been violated by the Soviet attack.
* What other diplomatic or legal avenues remain open for pressing claims.
* How the Soviet Union might respond if the US and other nations brought the KAL case to the World Court.
The Soviets do not accept the jurisdiction of the World Court in matters of this sort. But, as the US found in the Iranian hostage case, a favorable finding by the court can have a significant impact on world opinion, even if the guilty nation ignores the verdict.
Says a foreign policy expert on Capitol Hill: ''The US is a nation of laws. The Soviets are acting like a rogue. It is right that the US pursue this case through every possible legal channel until we get the issue resolved.''
While the Soviets might turn their backs on a World Court ruling, there is precedent for applying international law to the USSR.
Said Moynihan: ''At Nuremberg (West Germany), the Soviets . . . declared there was such a thing as crime under international law, that there was a higher law, a higher moral standard than that which was specifically embodied in the conventional treaty law. . . . So the Soviet Union took the lead in declaring the existence of crime under international law.''
While there seemed to be support for prosecuting the Soviets, Congress so far has been unwilling to direct Mr. Reagan on that or other specific steps.
As the Senate debated the KAL resolution last week, a string of tough amendments proposed by Sen. Jesse Helms (R) of North Carolina and others was voted down. But so great was Senate anger over the incident that some of the proposals came close to passing, despite opposition from the White House and the leadership of both parties in the Senate.
A Helms proposal to require that the President report to Congress on Soviet violations of existing arms control agreements lost by only 50-45. Another, barring Soviet imports produced with ''forced labor,'' lost 52-43.
When Sen. Walter D. Huddleston (D) of Kentucky then proposed that the number of Soviet officials in the US be reduced to the number of Americans in the Soviet Union, he lost by only a narrow 49-45 margin.
The final vote on the joint resolution condemning the Soviets was 416-0 in the House, 95-0 in the Senate.