Detained former president Rodrigo Duterte, who just won a mayoral comeback in Davao City, may not be able to take his oath of office — despite considerations that he could swear in before a Philippine consular official inside his cell at the Scheveningen Prison in The Hague, Netherlands.

Lawyer Kristina Conti, assistant to counsel at the International Criminal Court (ICC), explained in an interview on Sunday that a diplomatic or consular representative’s official powers are limited, including the authority to administer oaths only within Philippine territory or consular premises.

In that case, Duterte would have to leave his detention cell to take his oath of office at the Philippine Embassy in The Hague — something the ICC does not permit.

"A consul or diplomatic officer can visit Duterte in the context or on the assumption that they will discuss your rights and how they can provide assistance, but not administer an oath. The problem with the oath is that if you are a Philippine authority, you only have authority in Philippine territory, in your consulate office," Conti said. "But if you are in the Dutch territory, I don't know if the oath will be valid."

ICC-accredited lawyer Joel Butuyan had earlier raised similar concerns, noting that consuls have no power to conduct oath-taking ceremonies outside the embassy, as doing so would fall beyond Philippine jurisdiction.

Currently detained for crimes against humanity related to his bloody war on drugs, Duterte won the Davao City mayoral race in a landslide. The former chief executive garnered a commanding 662,630 votes, defeating his former Cabinet secretary Karlo Nograles, who received only 80,852 votes.

Interior Secretary Jonvic Remulla earlier said he would request the ICC’s permission to allow Duterte to take an oath of office before a Philippine consul inside the detention facility after his proclamation by the Commission on Elections (Comelec).

Vice President Sara Duterte, who returned to The Hague in time for her 47th birthday, announced that her father's legal team has begun discussing matters related to his oath-taking.

However, Conti dismissed that possibility, reiterating that while consular officers may be granted visitation rights, these do not extend to formal state functions like oath-taking ceremonies.

"Will they be allowed to visit [Duterte] with that intention? In fact, visitors are very restricted. Even Senator Imee Marcos was not able to visit [him]. It's not a place where anyone can in and out. Media are now allowed to visit, and detained people can't do propaganda," she argued. 

Pursuant to Section 11 of the Omnibus Election Code, Duterte has to take his oath of office within six months after his proclamation as elected Davao City mayor. Otherwise, the office will be considered vacant, "unless said failure is for a cause or causes beyond his control."

Duterte’s youngest son, Sebastian Duterte, the incumbent Davao City mayor, is expected to assume the responsibilities of acting mayor.

The ICC generally does not allow individuals awaiting trial to leave detention unless they have applied for interim release.

Duterte’s lead legal counsel, Nicholas Kaufman, previously confirmed that an application for the former president’s temporary release is already being prepared. However, lawyers representing the victims of Duterte’s drug war warned they would strongly oppose any such move.

They asserted that keeping Duterte in ICC detention is necessary to prevent him from posing a threat to victims and witnesses of his war on drugs.

The 80-year-old Duterte has been in ICC custody since his arrest on 11 March in Manila. He faces a single count of crimes against humanity in connection with 43 extrajudicial killings committed between 1 November 2011, and 16 March 2019, spanning his time as Davao City mayor and as president.

The ICC has argued that this period is within its jurisdiction, as the Philippines was still a member of the Rome Statute at the time. This counters objections that the court has no authority over Duterte since the country’s withdrawal as a state party in March 2019.

While the Philippine government officially recorded over 6,000 drug-related deaths during Duterte’s presidency, human rights watchdogs estimate the actual number may exceed 30,000, most of them from low-income communities.

The former president will remain detained in The Hague while awaiting the confirmation of charges hearing, scheduled for 23 September.