The decision by the 16-judge bench at the International Court of Justice will determine whether the David-versus-Goliath battle can continue to a full hearing, as Majuro seeks to shine a fresh spotlight on the threat of nuclear weapons.
The tiny Pacific island nation was ground zero for a string of nuclear tests on its pristine atolls between 1946-58, carried out by the United States as the Cold War arms race gathered momentum.
So the country of 55,000 people maintains it can testify with authority about the devastating impact of such arms.
Initially in 2014, Majuro accused nine countries of failing to comply with the 1968 nuclear Non-Proliferation Treaty, which seeks to inhibit the spread of atomic bombs.
But the ICJ set up in The Hague in 1945 to rule on disputes between states will only determine whether it is competent to hear three cases — against Britain, India and Pakistan.
The other countries — China, France, Israel, North Korea, Russia and the United States — have not recognised the court’s jurisdiction. Israel has also never formally admitted to having nuclear weapons.
The Marshall Islands maintained that by not stopping the nuclear arms race Britain, India and Pakistan continued to breach their obligations under the treaty — even if New Delhi and Islamabad have not signed the pact.
The treaty commits all nuclear weapon states “to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.”
Majuro is calling for the three nuclear powers to take “all necessary measures” to carry out what it considers to be their obligations under the treaty.
At a March hearing Majuro’s lawyers painted a vivid picture of the horrors seen after 67 nuclear tests were carried out on Bikini and Enewetak atolls.
“Several islands in my country were vaporised and others are estimated to remain uninhabitable for thousands of years,” Tony deBrum, a former Marshall Islands foreign minister, told the court.
The so-called “Operation Castle” tests in March and April 1954 were particularly devastating and resulted in massive contamination because of the nuclear fall-out.
“The entire sky turned blood-red,” said deBrum, who witnessed the explosion of the largest-ever US-built nuclear device called “Castle Bravo” as a nine-year old boy.
Yet critics argue that the ICJ action is a distraction and that the islanders’ real fight is with Washington, which carried out the tests in their backyard.
They contend that the case has no relation to the victims’ claims for increased compensation, better health care and clean-ups to render the sites habitable again.
Experts however say the islands hoped the three cases before the ICJ will thrust nuclear disarmament talks, which have stalled over the past two decades, back into the spotlight.
In 1996, the ICJ in another case issued a non-binding advisory opinion in which it urged the world’s nuclear powers to negotiate and reduce its stockpiles.
Even if the case may not have a direct impact, the Marshall Islands’ residents “perhaps feel that the more the difficulties with nuclear weapons are brought to the public consciousness, the better,” said Jens Iverson, assistant professor of Public International Law at Leiden University.
“They may hope that the world may become a safer place,” Iverson told AFP.
The case also comes amid a spike in tensions between India and Pakistan following renewed skirmishes in the disputed Kashmir region.
Pakistan and India have fought three wars since independence from Britain in 1947, two of them over the disputed Himalayan territory.
In 1998, the rival neighbours both demonstrated their nuclear weapons capability.