In hearings before the 15-judge panel earlier this year, India argued that the ICJ should annul the decision of Pakistan's military court and order the release of Kulbhushan Jadhav, a former Indian navy commander who was arrested in Pakistan in March 2016 and convicted of spying. Even if Jadhav is not released, says India, he should at least be given a trial beforw a civilian court.
India has also said that it should be given the right to arrange for Jadhav's legal representation and demanded full consular access.
"All eyes are set on today's verdict. Pakistan will be left exposed this time around as they have no accountability for justice. Kulbhushan is innocent and today we are hoping Indian diplomacy will finally bring good news for us and family of Jadhav," his friend Arvind Singh told WION ahead of the crucial verdict.
Watch: Will Jadhav get justice on World Justice Day?
While Pakistan has sent a 13-member team to the ICJ for today's verdict, India is being represented by Joint Secretary Deepak Mittal and officers from the Legals and Treaties Division of the Ministry of Expertan Affairs.
The death sentence, given by a military court in Pakistan, had evoked sharp reactions in India.
India filed a claim against Pakistan before the ICJ in May 2017 arguing Islamabad had breached the 1963 Vienna Convention by not allowing diplomatic assistance to Jadhav during his secretive trial. Harish Salve, who was representing India in the case, questioned the functioning of Pakistan's notorious military courts and urged the top UN court to annul Jadhav's death sentence, which is based on an "extracted confession".
India won an injunction that ordered Jadhav's execution stayed while the court looked into the case.
Pakistan said that India was trying to use the court intended to resolve international disputes as a criminal appeals court. They also said the relief sought by India was disproportionate even if the treaty were violated, and at most Jadhav's case could be reviewed.
The ICJ is the United Nation's highest court, and its decisions are binding - though it has no power to enforce them and they have been ignored in rare instances.
The death sentence, given to Kulbhushan Jadhav by a military court in Pakistan, had evoked sharp reactions in India