PARIS — The traditional Muslim veil has long been a source of conflict in the West over integration and gender equality. Now, another familiar practice is prompting debate: the handshake.

Last week, it was reported that a Muslim couple had been denied Swiss citizenship after refusing — for religious reasons — to shake hands with people of the opposite sex during their interview. Officials cited a lack of respect for gender equality as the reason for their decision.

It is not the first time the topic of handshakes has caused a stir in the country. In 2016, two Syrian immigrant brothers refused to shake their female teacher's hand, arguing that Islam did not permit physical contact with a person of the opposite sex who is not a family member. Shaking the teacher's hand before and after class is a long-standing tradition in Switzerland, and the regional educational authority ruled that parents of children who refuse would face a fine. Swiss Muslim groups disagreed over whether the brothers were justified in refusing.

The Swiss Federal Court has previously rejected a local ban on wearing hijabs in schools. The board of education, however, ruled that forcing the students to shake the teacher's hand was a reasonable intrusion on their religious beliefs, since "it did not involve the central tenets of Islam," The New York Times reports.

Hafid Ouardiri, a Swiss mediator who is active in the fight against radicalization, told Geneva-based newspaper Le Temps: "We need to take this case very seriously. It is unacceptable that these students refuse to shake their teacher's hand in the name of Islam … Above all, our religion teaches respect." The newspaper asked whether the refusal could be the sign of a "slide" towards radicalism, after one of the boys posted videos of soldiers on Facebook in which there was "no explicit violence, but a black flag, identical to those used by the Islamic State group, was visible."

She puts her hand to her heart.

Also last week, a Swedish Muslim woman won compensation after her job interview was cut short when she refused to shake the male interviewer's hand. Sweden's Labor Court ruled that she had been discriminated against, since there was no evidence her refusal would cause difficulties in her work as an interpreter, The Local reports. The woman had argued that when both men and women are present, she greets them the same way, by putting her hand to her heart.

France, where the battle over the Muslim veil has been a major issue for years, has also found itself at the center of the handshake debate. In 2017, an Algerian women was denied citizenship after she refused to shake the hand of a senior official during her naturalization ceremony. Le Figaro reports that the ruling was recently upheld by the Council of State, France's highest administrative jurisdiction. The government claimed that the actions of the woman, who has been married to a French man since 2010, "reveal a lack of assimilation."

The question of gender boundaries is not limited to Islam. When Mike Pence became Vice President of the United States, an interview from 2002 resurfaced in which the evangelical Christian revealed that he never eats alone with a woman other than his wife. A 2015 survey by National Journal found that several female aides in Washington reported being barred from "driving alone with their congressman or senator, or even sitting down one-on-one in his office for fear that others would get the wrong impression," reports The Atlantic. The magazine argues that similar policies harm women's progress by cutting them off from powerful people for long parts of the day.

Also Orthodox Judaism has rules forbidding a man from touching a woman who isn't his wife. Earlier this year, a Jewish candidate in a local election in Antwerp, Belgium, caused controversy by initially refusing to shake hands with women, the Flanders news site VRT NWS reports. He planned to run representing the Christian Democratic and Flemish party (CD&V). One of the party's leaders, Hendrik Bogaert, wrote on Twitter that a man who refuses to shake a women's hand "doesn't belong on a CD&V list."