Yesterday, the European Court of Justice ruled that a company's internal policy that prohibits "visible wearing of any political, philosophical or religious sign" is not directly discriminatory. The ruling centered around two cases of Muslim women who accused their employers of discriminating against them for wearing their hijabs to work. The two cases differed in that one woman's employer had an internal dress code policy, and the other's did not. The court noted that if a company lacks an internal dress code, the argument for discrimination against headscarfs is stronger.
See "E.U. court says employers can ban Muslim headscarf in workplace", James McAuley, The Washington Post, March 15, 2017