|Deserted Paguna mine. Getty Images|
The ruling, by the United States Court of Appeal, ends a legal battle launched in 2000 by thousands of Bougainvilleans, represented by Seattle lawyer, Steve Berman.
The case was based on a claim that the London-based mining company conspired with the PNG government to quell civil resistance on Bougainville to its Panguna copper mining operation, causing thousands of deaths.
In 2010, the appeal court ruled that the case could be heard under an 18th century ruling, allowing foreigners injured by a violation of international law to take legal action in the US.
But Reuters reports that after an April Supreme Court ruling overturned that decision, Mr Berman asked the appeal court to return the case to the Los Angeles district court so the plaintiffs could proceed with other claims.
A panel of 11 appeal court judges, used as a precedent an earlier Supreme Court ruling, that limited the scope of the Alien Torte Statute or the US District Court jurisdiction, to hear international law violations occurring in the United States.
It was agreed in that ruling that violations elsewhere must "touch and concern" US territory "with sufficient force" to overturn that definition.