Haiti, torn by weeks of unrest and decades of misgovernment, badly needs its newly appointed prime minister, Gérard Latortue, to succeed. Yet Mr. Latortue did himself no favors on Saturday by going out of his way to embrace some of the unsavory thugs who helped oust the country’s last elected president, Jean-Bertrand Aristide. Successive Haitian governments have compromised their own legitimacy by using criminal gangs as enforcers. Mr. Latortue needs to end this disastrous pattern, not perpetuate it.

Mr. Latortue has no democratic mandate. Haitians are bitterly split between Aristide supporters and opponents, and both sides are heavily armed. Clearly, he needs to reach out to those on both sides of this divide who want to move their country forward. But Mr. Latortue aided neither national reconciliation nor his own shaky legitimacy by the unseemly ceremony he took part in last Saturday.

Ferried by American military helicopters to the city of Gonaïves, where the anti-Aristide revolt began, he stood on a stage with killers like Jean-Pierre Baptiste. Mr. Baptiste, who escaped from prison in 2002, is a death squad leader convicted of participating in a 1994 massacre of Aristide supporters.

Also welcoming Mr. Latortue to Gonaïves was Guy Philippe, the rebel military chief, who has yet to keep his promise to American commanders to disarm his fighters. While there, the prime minister unwisely paid tribute to Amiot Métayer, the murdered founder of the Cannibal Army, an initially pro-Aristide gang. In 2002, Mr. Métayer was jailed at the behest of the Organization of American States. Freed by his supporters the next month, he turned against President Aristide and was later murdered. Mr. Métayer’s followers began the revolt that toppled the elected government.

Until Haiti can hold fair elections, Mr. Latortue derives his authority from the American-led occupation force. His mistakes damage not just his reputation, but Washington’s as well.