A maritime border deal under which Iraq and Kuwait share a key waterway into the Arabian Gulf has been struck down by Baghdad's top judges.
The Iraqi Federal Supreme Court annulled the law ratifying a 2012 agreement between the neighbouring countries that regulated maritime navigation on the crucial waterway.
The ruling on Monday, on a case filed by Iraqi MPs last month, said the 2013 law was unconstitutional.
It should have been ratified with the approval of two thirds of Parliament, not a simple majority, judges said.
Khor Abdullah is Iraq's only entrance to the Gulf, through which by far most of its oil exports flow, alongside its imported goods.
The deal, which has its origins in the First Gulf War, draws a line in the middle of Khor Abdullah and stipulates that "each party shall exercise its sovereignty over that part of the waterway which lies within its territorial water".
Critics consider the agreement unfair, saying Kuwait has no right to control any part of Khor Abdullah, historically known as an Iraqi canal.
In 2013, the Parliament approved the agreement with a simple majority.
The deal details that it “shall remain in effect indefinitely, and either party may terminate it with written notice to the other party, provided that a notice period of six months is given and termination is subject to the mutual consent of both parties”.
Any dispute arising between the two parties in implementing the agreement shall be resolved amicably through discussions or referred to the International Tribunal for the Law of the Sea, the agreement says.
Legal expert Ali Al Timimi says the ruling revokes the existing accord.
“The decision of the Federal Court shall be considered final and binding on all authorities,” Mr Al Timimi told The National.
“This agreement has been cancelled unilaterally and in this case, the issue will be taken to the International Tribunal for the Law of the Sea."
It is unclear how the government and Parliament will deal with the ruling or whether the legislature needs to reapprove the agreement. Government officials were not immediately available to comment.
UN ruling after invasion
Three years after Iraqi autocrat Saddam Hussein’s 1990 invasion of the oil-rich country, the UN Security Council demarcated the land border under a resolution, granting Kuwait territory that had previously been held by Baghdad.
The maritime border was left for the two sides to resolve.
In July, Kuwaiti Foreign Minister Sheikh Salem Al Sabah visited Baghdad and both sides vowed to resolve the pending issues, mainly the maritime border demarcation beyond Khor Abdullah and the joint oilfields.
They then announced that the technical-legal committee on the maritime border would meet in Baghdad on August 14, followed by a visit from the Kuwaiti Oil Minister and his delegation on September 10.
The visit by Sheikh Salem sparked public outcry with Iraqis accusing the government and politicians of handing over more land and maritime borders to Kuwait, mainly parts of Umm Qasr port.
The Iraqi government denied the accusations, saying it was implementing the 1993 UN resolution.
Several politicians have alleged that some who assumed senior government positions were bribed by Kuwait to offer concessions. No proof has been offered of their allegations and no case has been referred to court.
Early last year, Iraq paid its final war reparations to Kuwait, settling the $52.4 billion of claims made for damage inflicted during the 1990 invasion.
Kuwait is also in dispute with Iran over their maritime border and Al Durra offshore gasfield in the Arabian Gulf.
Kuwait and Saudi Arabia say they have “exclusive rights” to Al Durra and called on Iran to validate its claim by demarcating its maritime borders.
Iran previously claimed a stake in the field and said a Kuwaiti-Saudi agreement signed last year to develop the field was illegal.