What is an ‘état de siège’? No one seems quite sure.

Not long after Haiti’s president was shot to death by assassins who burst into his home early Wednesday, the country’s interim prime minister announced that he had declared an “état de siège” — a state of siege.

To many people around the world watching with alarm as events unfold in Haiti, the term was unfamiliar, even baffling.

But things grew a little clearer when the interim prime minister, Claude Joseph, published details of the order in the official government journal, Le Moniteur.

Haiti is now basically under martial law. For 15 days, the police and members of the security forces can enter homes, control traffic and take special security measures and “all general measures that permit the arrest of the assassins” of President Jovenel Moïse. It also forbids meetings meant to excite or prepare for disorder.

There is one wrinkle. Or two, really.

Only Parliament has the power to declare a state of siege, said Georges Michel, a Haitian historian and constitutional expert. But Haiti at this moment has no functional Parliament. The terms of the entire lower house expired more than a year ago, and only 10 of Haiti’s 30 Senate seats are currently filled.

“Legally, he can’t do this,” Mr. Michel said. “We are in a state of necessity.”

There are actually a few other wrinkles.

Mr. Joseph’s term as interim prime minister is about to end and, in fact, President Moïse had already appointed a replacement, his sixth since taking office.

“We are in total confusion,” said Jacky Lumarque, rector of Quisqueya Universty, a large private university in Port-au-Prince. “We have two prime ministers. We can’t say which is more legitimate than the other.”

It gets worse.

Haiti also appears to have two Constitutions, and the dueling documents say different things about what to do if a president dies in office.

The 1987 version — published in both national languages, Creole and French — deems that if the presidency is vacant for any reason, the country’s most senior judge should step in.

In 2012, however, the Constitution was amended, and the new one directed that the president should be replaced by a council of ministers, under the guidance of the prime minister. Except if, as was Mr. Moïse’s situation, the president was in the fourth year of office. In that case, Parliament would vote for a provisional president. If, of course, there were a Parliament.

Unfortunately, that Constitution was amended in French, but not in Creole. So as it stands, the country has two Constitutions.

“Things are unclear,” said Mr. Michel, who helped write the 1987 Constitution. “It’s a very grave situation.”

Mr. Lumarque lamented the state of his country.

“This is the first time where we’ve seen that the state is so weak,” he said. “There is no Parliament. A dysfunctional Senate. The head of the Supreme Court just died. Jovenel Moïse was the last legitimate power in the country’s governance.”