Denying that mass killings of Armenians in Ottoman Turkey in 1915 were genocide is not a criminal offense, but denying the Jewish Holocaust in World War II is, the European Court of Justice ruled on Tuesday in a case involving Switzerland.

The court, which upholds the 47-nation European Convention on Human Rights, said a Swiss law against genocide denial violated the principle of freedom of expression.

The ruling has implications for other European states, such as France, that have tried to criminalize the refusal to apply the term “genocide” to the massacres of Armenians during the breakup of the Ottoman empire.

In 2007, a Swiss court in Lausanne convicted the leader of the leftist Turkish Workers’ Party, Doğu Perinçek, of violating laws against racism by denying the Armenian genocide. While speaking at a number of conferences in Switzerland in 2005, Perinçek had called talk of an Armenian genocide “an international lie.” Perinçek appealed the verdict twice in Swiss courts, but the conviction was upheld. Eventually he took his case to the European Court of Justice.

Turkey accepts that many Armenians died in partisan fighting or from hunger in 1915 and during several years after that, but denies that up to 1.5 million were killed and that it constituted an act of genocide — a term used by many Western historians and foreign parliaments.

Genocide is “a very narrow legal concept” that is “difficult to substantiate,” the court said, adding, “Mr. Perinçek had engaged in speech of a historical, legal and political nature which was part of a heated debate.”

The court drew a distinction between the Armenian case and appeals it has rejected against convictions for denying the Nazi German Holocaust against the Jews during World War II.

“In those cases, the applicants had denied the historical facts even though they were sometimes very concrete, such as the existence of the gas chambers. They had denied the crimes perpetrated by the Nazi regime for which there had been a clear legal basis. Lastly, the acts that they had called into question had been found by an international court to be clearly established.”

The judges cited a 2012 ruling by France’s Constitutional Council which struck down a law enacted by the government of then-President Nicolas Sarkozy as an unconstitutional violation of the right to freedom of expression and freedom of research.

The ruling is binding for all European institutions and European Union member states. The verdict will also affect France, where a government-sponsored bill proposing to ban denial of the Armenian Holocaust was rejected a year and a half ago. According to French media, the present government is planning to resubmit the bill, in an attempt to outlaw denial of the Armenian genocide.

Switzerland has three months to appeal against the ruling.