Pakistan's parliament has voted to give army chief Field Marshal Asim Munir new powers and lifetime immunity from arrest and prosecution, a move that critics say paves the way towards autocracy.

The 27th constitutional amendment, which was signed into law on Thursday, will also make significant changes to the way the country's top courts operate.

Those defending the changes say they provide clarity and administrative structure to the armed forces, while helping to ease a backlog in the courts.

Pakistan's military has long played a prominent role in the nuclear-armed country's politics - sometimes seizing power in coups, and, on other occasions, pulling levers behind the scenes.

Throughout its history, Pakistan has oscillated from more civilian autonomy to overt control under military leaders like General Pervez Musharraf and General Zia-ul-Haq. Analysts refer to the balance between civilian and military as hybrid rule.

Some see the amendment as a sign that the balance is shifting in the military's favour.

'For me, this amendment is the latest indication, perhaps the strongest yet, that Pakistan is now experiencing not a hybrid system, but a post-hybrid system,' says Michael Kugelman, director of the Wilson Center's South Asia Institute in Washington. 'We're essentially looking at a situation where the civil-military imbalance is about as imbalanced as it could possibly be.'

The latest amendment means that Munir, who has been army chief since November 2022, will now also oversee Pakistan's navy and air force.

His field marshal title and uniform are for life and he will be given 'responsibilities and duties' even after retirement determined by the president with the advice of the prime minister.

The expectation is that this will give him a prominent role in public life for as long as he is alive.

Supporters of the bill have argued it clarifies Pakistan's military command structure.

Pakistan's government-operated news agency, the Associated Press of Pakistan, cited Prime Minister Shehbaz Sharif as saying that the changes were part of a broader reform agenda to ensure Pakistan's defence keeps pace with modern warfare requirements.

But others see it as ceding power to the military.

'There is no balance between the military and the civilians,' says Munizae Jahangir, journalist and co-chair of the Human Rights Commission of Pakistan. 'They have tilted again that power dynamic towards the military and empowered the military at a time when the military needed to be reined in.'

The second controversial area of change are the courts and judiciary.

Under the amendment a new Federal Constitutional Court (FCC) will be created which will determine constitutional questions. The FCC's first chief justice and the judges that serve in it will be appointed by the president.

'It forever changes the shape and the nature of the right to a fair trial,' says Ms Jahangir.

'The influence of the executive has increased not just in appointing judges but also constitutional benches. When the state is dictating the constitution of those benches then what hope do I have as a litigant of getting a fair trial?'

In the hours after the amendment was signed into law, two Supreme Court justices handed in their resignations, highlighting growing discontent within the judiciary.

Justice Athar Minallah expressed that the constitution he swore to uphold is no more, while Justice Mansoor Ali Shah remarked that the judiciary had been brought under the control of the government.

The implications of the amendment signal significant political shifts in Pakistan, aligning with increasing militarization of government structures and escalating fears of authoritarianism.