Ayatollah Ali Khamenei, Iran’s Supreme Leader, was killed by airstrikes in the early days of the current war. Reports from this week’s Arba’in pilgrimage suggest that loss is still shaping public feeling among Shia Muslims well beyond Iran’s borders.

It also raises a question that is religious before it is political: who chooses a Supreme Leader, and on what basis?

What the role actually is

Iran has an elected president and parliament, but the Supreme Leader sits above both. The office holds final authority over the armed forces, the judiciary, state broadcasting and the broad direction of foreign policy.

The position is not merely administrative. It rests on a religious argument — that in the absence of the awaited twelfth Imam, a qualified jurist should exercise guardianship over the community. That doctrine, usually rendered as velayat-e faqih, is the foundation of the Islamic Republic’s structure.

Who does the choosing

Selection falls to the Assembly of Experts, a body of Islamic scholars elected by the public. The Assembly is charged with identifying the candidate best qualified in religious learning, justice and political capability, and it also has the formal power to remove a leader who ceases to meet those criteria.

Its independence is limited in practice. Candidates for the Assembly must be approved by the Guardian Council, half of whose members are appointed by the Supreme Leader — so a leader shapes the body that will eventually choose a successor.

How the doctrine came to power

The arrangement is younger than many readers assume. For most of Shia history, senior clerics did not govern. They taught, issued rulings, administered religious taxes and often kept a deliberate distance from rulers they regarded as illegitimate.

The argument that a qualified jurist should hold political authority in the absence of the awaited Imam was developed and popularised in the twentieth century, most prominently by Ayatollah Ruhollah Khomeini, and put into practice after the 1979 revolution.

It was contentious among clerics at the time and remained so afterwards. Several senior figures who had supported the revolution disagreed sharply with the structure that emerged from it.

This matters for reading the news: the Iranian system represents one interpretation, roughly fifty years old, of a tradition considerably older.

Where religious authority actually comes from

In Shia Islam, the most learned scholars — those recognised as sources of emulation — attract followers who choose to follow their rulings on religious questions. That following is voluntary and is built through decades of teaching, published scholarship and reputation.

Crucially, it does not follow national borders and cannot be assigned by any government. A believer in Lebanon, Iraq, Pakistan or Bahrain chooses whom to follow, and may well choose a scholar in a different country from the one they live in.

So a state can appoint someone to an office. It cannot appoint someone to religious authority. Where the two coincide, the office is strong; where they diverge, an official position can be held by someone whom many believers do not treat as their guide at all.

Not all Shia clerics agree

This is the part most often missed in Western coverage. The doctrine underpinning the office is contested within Shia Islam itself.

A significant scholarly tradition — associated particularly with the seminaries of Najaf in Iraq — holds that clerics should guide believers on religious matters while remaining outside the machinery of government. On that view, direct clerical rule risks damaging the faith by binding it to the failures of any administration.

So Shia Islam does not entail the Iranian system. Iran’s system is one interpretation, disputed by respected authorities elsewhere.

Why a killing complicates a succession

A leader who dies after a long illness leaves time for arrangements to be made quietly. One killed suddenly, by a foreign power, does not.

Beyond the procedural difficulty, there is the matter of authority itself. Religious standing is built over decades and cannot be transferred by appointment. A successor may inherit the office while inheriting far less of the deference that made the office work.

What follows from that is genuinely uncertain, and anyone claiming to know is guessing. What can be said is that the question is being decided inside a religious tradition with its own rules — not only in the terms of the war being fought around it.

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Sources: NPR, 6 August 2026; Al-Monitor. Background on the constitutional structure of the Islamic Republic of Iran.