The court matters date back to early August when parliament voted in Peter O'Neill as prime minister while Somare was on extended medical leave.
But the parliamentary procedures and constitutional legitimacy behind this move was questionable and on December 12 the Supreme Court ruled that Somare remained the rightful PM in a split 3:2 decision.
As the O'Neill-Namah coalition dominated parliament, the court ruling was ignored. Laws were passed, including retrospective laws, to maintain this government. Speaker Jeffery Nape even briefly became an acting governor-general.
This coalition has effectively remained PNG's government while matters over the legitimacy of it have remained before the court. In recent months this government has even passed controversial laws aimed at curtailing the powers of the judiciary.
With parliament recently closing ahead of the midyear election, it appears that the judiciary has struck back.
Yesterday the Supreme Court ruled that Somare was the rightful PM. Chief Justice Sir Salamo Injia and two other judges supported this decision while the other two judges abstained.
That Injia supported this decision for a second time is of no great surprise. A target of the O'Neill-Namah coalition, Injia was arrested in March over claims he illegally diverted funds from the estate of a deceased judge. But these proceedings quickly stalled because the prosecution needed to "gather evidence".
The legal significance of the recent court decision means that all laws made by the O'Neill-Namah government could be declared void - including the Judicial Conduct Act.
In a press conference yesterday O'Neill told local media that his government, which should be in caretaker mode as an election nears, would not recognise the Supreme Court decision.
According to The National, he believed the fact that two judges abstained was evidence that corruption was at play and he said police will begin investigating the judiciary.
"The courts should know that we are in the process of having new leaders elected and such a decision is not timely for the stability of the country," O'Neill reportedly said.
Importantly, O'Neill told the PNG newspaper that the election was still on despite the Supreme Court ruling.
A special sitting of parliament is expected today. Going by the precedent set last time, new laws are likely to be introduced and passed.
ABC's PNG correspondent Liam Fox tweeted that the special sitting might be moved to 2pm local time and that no politicians were in Parliament.
Meanwhile, Somare has called on the police and public service to honour the Supreme Court ruling.
"The O'Neill-Namah regime hijacked parliament and took the country on a dangerous and risky ride, the full implications of which may not be clear for some considerable period," Somare said.
"They introduced a number of retrospective and vindictive pieces of legislation in an attempt to camouflage their illegitimacy. In the process personal accusations were being made against me and a small group of members of parliament that resisted the forces of tyranny.
"I believe upholding the rule of law and protecting the Constitution is one of my last and most important challenges as a member of parliament."
While the O'Neill-Namah government sought to delay the election by six months, in recent weeks it finally succumbed to domestic and international pressure to keep the existing timeframes.
Polling will start on June 23 and continue through to July 6. The election writs are due back on July 27.
There is uncertainty over whether Somare, who was PNG's first PM, will contest the election or not.