PARIS — “Liberté, Égalité, Fraternité” is not just France’s motto, it is the law. In fact, the nation’s highest constitutional tribunal decreed on Friday, it can now be a defense against prosecution.
In a landmark decision, the Constitutional Council said that a French farmer was not guilty of a crime when he smuggled migrants into the country because he acted under “the principle of fraternity.”
The national motto is enshrined in the Constitution in two places, the council noted, which trumps the statute making it a crime to help someone enter the country illegally.
The council’s ruling came in the case of Cédric Herrou, an olive grower, who was charged with shepherding migrants across the French-Italian border and into southern France’s Roya Valley.
He became something of a folk hero, with his supporters comparing him to the organizers of the Underground Railroad, but a court convicted him last year on charges of helping migrants and fined him 3,000 euros, or about $3,200.
The Constitutional Council ruled on Friday, however, that Mr. Herrou acted within his rights. “The principle of fraternity confers the freedom to help others, for humanitarian purposes, regardless of the legality of their presence on national territory,” the council said, in a ruling that suggested the same defense would not apply to those who traffic migrants for money.
In a statement, the council said the ruling was the first in which it found “that fraternity is a constitutional principle.”
No constitutional principle guarantees foreigners the right to enter or remain in the country, and fighting illegal immigration is a legitimate government function, the court wrote. But, it added, “it is up to the legislator to reconcile the principle of fraternity and the safeguarding of public order.”
Under French law, a person who smuggles foreigners into the country faces up to five years in prison and a fine of up to €30,000.
A 2012 law allows people to provide aid to migrants, like food and shelter, for humanitarian reasons, but Mr. Herrou went further, organizing like-minded volunteers to lead people through mountain passes in the rugged terrain northeast of Nice.
During his highly publicized trial, the prosecutor requested an eight-month sentence, but public opinion appeared to be on the defendant’s side. Though the court convicted him, it declined to send him to prison and imposed a penalty that was widely seen as a light.
At trial, Mr. Herrou defended his actions, questioning the morality of what he called an “ignoble” policy of turning away refugees. “I am a Frenchman,” he said.
“There are people dying on the side of the road,” he told the court. “It’s not right. There are children who are not safe.”
His reaction to the ruling on Friday was more muted. “In the name of fraternity, we will remain united,” he wrote on Twitter.
Border patrol officers turned back more than 85,000 migrants who tried to enter France in 2017, according to figures made public by the migrant charity La Cimade, with more than 46,000 of those refusals occurring at the French-Italian border.
“The law states that we shouldn’t help migrants, but it also says that we shouldn’t leave them in a dangerous situation, so what can we do?” Vincent Gasquet, a pizza chef who aids migrants at the border near Briançon, told The New York Times in January.
Mr. Gasquet said he admired the work of Mr. Herrou, adding: “The line is so thin, but solidarity and fraternity should prevail.”
Elian Peltier reported from Paris, and Richard Pérez-Peña from London. Anne-Sophie Bolon contributed reporting from London.