The court was due to decide on five petitions against amendments that plaintiffs say were bulldozed through the House of Representatives in March without proper public consultation, amid concerns of an expansion of the military's involvement in civilian life under President Prabowo Subianto. 

Fears are growing in the country that Prabowo is turning increasingly to the armed forces to help deliver his ambitious agenda after just 11 months in office, reviving memories of the military-dominated 1966-1998 New Order era of authoritarian rule.

Prabowo has appointed former generals to key posts and has deployed the military for various tasks, including handling street protests, implementing initiatives on free school meals and food security, manufacturing medicines and seizing palm oil plantations for a new state-owned firm. 

The rulings come at a time of festering anger following two weeks of at times violent demonstrations over issues from lawmakers' allowances and state budget priorities to police conduct and perceptions of creeping militarisation in Indonesia, presenting Prabowo with his first major test. 

In early September, the military was deployed in the capital after six the nationwide protests.

In the wake of the protests, police set up checkpoints across the capital, while officers and the military conducted city-wide patrols and deployed snipers in key locations.

The petitions argue the amendments to TNI law lacked transparency and public participation before being passed by a parliament overwhelmingly allied with the president, and have called for the changes to be annulled. 

"We expect the court to repeal the military law because the process is not in accordance with another law regulating legislative process," petitioner Ardi Manto Adiputra told Reuters, adding lawmakers had met in secret to discuss revisions to the law and had rushed its passage. 

The petitioners include human rights and student groups and Inayah Wahid, the daughter of Indonesia's former President Abdurrahman Wahid. 

Indonesia law minister has said the legislative process was above board and public input had been sufficiently sought. 

The court decision is not expected to address the revisions to the law, but the processes that took place before it was passed. 

Ardi said his group planned to file another judicial review over the substance of the legislation at a later stage. 

He also said the court decision would be delivered virtually, with neither plaintiffs nor the public permitted to attend the verdict in person.