Duterte's first night in a jail cell is a pivotal moment for the ICC

Outside the International Criminal Court's (ICC) detention centre, where former Philippines president Rodrigo Duterte was taken on Wednesday, his supporters gathered, waving national flags and shouting, "Bring him back!" as he was driven through the imposing iron gates at speed.

Shortly before he landed in the Netherlands, the 79-year-old unapologetically defended his bloody "war on drugs" for which the ICC says there are "reasonable grounds" to charge him with murder as a crime against humanity.

Small-time drug dealers, users and others were killed without trial on his watch as mayor and, later, as president.

The official toll stands at 6,000, though activists believe the real figure could run into the tens of thousands.

Duterte said he cracked down on drug dealers to rid the country of street crimes.

However, rights groups allege that the campaign was rife with police abuse, targeting young men from the urban poor.

Duterte is the first Asian former head of state to be indicted by the ICC - and the first suspect to be flown to The Hague in three years.

And his arrival comes at a pivotal moment for the International Criminal Court.

How did Rodrigo Duterte end up in a jail cell?

Rodrigo Duterte's arrest and deportation on Monday was the result of an unprecedented chain of events.

His supporters allege that the ICC is being used as a political tool by the country's current president Ferdinand Marcos who has publicly fallen out with the powerful Duterte family.

The ICC is a court of last resort designed to hold the most powerful to account when domestic courts are unable or unwilling to do so. But this case is a reminder of the extent to which it depends on state cooperation in order to fulfil its mandate - it effectively has no power to arrest people without the cooperation of the countries they are in, which is most often refused.

In the case of Duterte, chances that he would ever be prosecuted by the ICC seemed unthinkable even in 2022, when his daughter, Vice-President Sara Duterte, allied with Marcos to create the powerful "uniteam" that swept parliamentary elections.

Up until a few months ago, Marcos had dismissed the idea of cooperating with the ICC.

But the pace at which Duterte was served an arrest warrant and extradited shows that when political winds shift, those once considered untouchable can find themselves touching down in The Hague.

Duterte will spend his 80th birthday in the ICC's detention facility, located in the dunes of The Hague

The whole process of his extradition - from his detention in Manila to his arrival in The Hague - has been documented on social media by his daughter Kitty and Duterte himself through his aide. His plane was the most tracked on flight radar.

"I am the one who led our law enforcement and military. I said that I will protect you and I will be responsible for all of this," he said on a Facebook video, one of many that was shared over more than 24 hours during his journey from Manila to The Hague.

It provided rare insight into what is usually an opaque process, and the world was able to follow, sometimes in real time, every step of it right down to the meals Duterte was served on board his chartered jet.

A much-needed win for the ICC?

Duterte's arrest now sends a strong signal that even powerful individuals may be held accountable for their actions, potentially deterring future abuses.

His case has also reignited debate about the ICC's role in relation to national sovereignty, a concern often raised by non-member states like the United States, Russia, and China.

The court depends on its 128 members to fund and be the operational arm of this judicial body.

So Duterte's headline-making arrival, followed by his first night in a jail cell at The Hague, offer the the court a much-needed win.

After serving two high-profile arrest warrants – one for the Russian president Vladimir Putin, and another for Israel's prime minister Benjamin Netanyahu over the war in Gaza – which are unlikely to be enforced any time soon, the arrival of Duterte will be put forth as proof the court is capable of bringing those accused of the gravest atrocities to face justice.

It is a litmus test for the ICC's ability to function effectively in an increasingly polarised climate.

ICC prosecutor Karim Khan was recently sanctioned by Donald Trump over the arrest warrant issued for Benjamin Netanyahu.

The detention of Duterte provides him with a powerful response.

"Many say international law is not strong," Karim Khan acknowledged. "But international law is not as weak as some may think. When we come together, when we build partnerships, the rule of law can prevail."

Duterte's arrest offers the ICC a much-needed win in an increasingly polarised climate

The former Philippines president will now mark his 80th birthday this month in the ICC's detention facility, located in the dunes of The Hague.

The facility, once a Nazi prison complex, provides each detainee with a private cell, access to computers, a library, and sports facilities.

If he isn't satisfied with the meals provided, Duterte has the option to prepare his own food using a shopping list in the detention center's kitchen. He will also have access to medical care, lawyers, and visitors.

He is expected to make his initial court appearance in the coming days, where he will confirm his identity, choose the language he wishes to follow proceedings in, and acknowledge the charges against him.

Following this public appearance, a confirmation of charges hearing will follow, during which the judges will decide whether the prosecution has presented a sufficient amount of evidence to proceed to trial.

If the charges are confirmed, it could be many months before he eventually goes on trial, and years before a final judgment.