No date was set for a ruling.
The case, referred last June to the European Court of Human Rights, concerns the case of Dogu Perincek, a Turkish national and chairman of the left-wing Turkish Workers’ Party. Perincek was found guilty of racial discrimination in Switzerland for describing the so-called "Armenian genocide" as an "international lie."
At the hearing, Amal Alamuddin, a lawyer representing the Armenian government, said a lower court had not taken into account documents from 1915, when the events are alleged to have occurred.
Alamuddin also said that, according to a story from that period that appeared in New York Times, Talat Pasha had decided to expel the Christians from Anatolia, the Asian part of what is now Turkey.
Talat Pasha was a member of a triumvirate that governed the Ottoman Empire during World War II. He was assassinated in Berlin in 1921 by a survivor of the Armenian relocation.
"There are no court trials where Talat Pasha was convicted," said Perincek at the hearing Wednesday. "As a result of a probe by the British state, the case was closed as no evidence could be found about the Armenian issue."
Perincek called Talat Pasha a hero of liberty.
The defendant recalled a book written by Armenia's first prime minister, Ovanes Katchaznouni, that detailed a dialogue between the prime minister and the pasha.
In the events that led to the present case, Perincek, at various conferences in Switzerland in 2005, rejected allegations that the events of 1915 and the following years in the Ottoman Empire amounted to "genocide" of the Armenian people.
The Switzerland-Armenia Association filed a criminal complaint against him. Perincek was tried by the Lausanne Police Court in March, 2007, found guilty of racial discrimination, and fined.
Many Armenians argue that denying allegations that the events of 1915 constituted "genocide" should be a crime, just as negating the Holocaust is. In 2003, the National Council of Switzerland, the country's parliament, recognized the events of 1915 as "genocide."
Turkey officially refutes this description, saying that although Armenians died during relocations many Turks also lost their lives in attacks by Armenian gangs.
A Swiss Appeals Court subsequently confirmed Perincek's sentence. Perincek then appealed to the Federal Tribunal, the highest court in Switzerland, which also confirmed the sentence.
In 2008, Perincek appealed to the European Court of Human Rights in Strasbourg, claiming that the Swiss courts had violated his rights, including that to freedom of expression. He demanded compensation of 140,000 euros for moral and financial damages, as well as court expenses.
Now, after a hearing by the court's 17-member Grand Chamber, the court will begin its deliberations, to be held in private.
Turkish Foreign Minister Mevlut Cavusoglu said Wednesday that the Swiss courts' decisions contradicted freedom of expression laws and the legal precedents of the European Court of Human Rights.
"(The case) is not about the genocide issue but is over freedom of expression," Cavusoglu said during a visit to Turkmenistan.
Separately, Turkey has called for a joint Armenian-Turkish research project into the events, making use of the archives in both countries, to establish the facts.
In April 2014, Turkish President Recep Tayyip Erdogan, who was prime minister at the time, offered condolences for the Armenian deaths that occurred in 1915 -- a first for a Turkish leader. The move was seen as a significant step toward possible reconciliation.