Apart from its own case law and two cases from the Conseil d'État, the Council refers to four ECtHR cases:
- Kokkinakis v. Greece (1993) (par. 31)
- Leyla Şahin v. Turkey (2005) (par. 104-111)
- Dogru v. France (2008) (par. 47-48)
- Ahmet Arslan and others v. Turkey (2010) (par. 34-36)
Kokkinakis is a case about proselytising Jehova's Witnesses in Greece, which was apparently a crime. This law was held (6-3) to be in violation of art. 9 freedom of religion. It was cited as authority for the proposition that the freedom of religion implies more than only the freedom to have a religion, i.e. that it includes the "freedom to "manifest [one's] religion". Bearing witness in words and deeds is bound up with the existence of religious convictions."
Arslan, which concerned a terrorism suspect who refused to take of his turban in court, as well as the headscarf cases of Şahin and Dogru are obvious precedents to consider if you're trying to figure out how to do the proportionality analysis in these circumstances. However, the strange thing is that the Council seems to cite them more for the scope of the freedom of religion in the first place, which seems to be covered by Kokkinakis just fine. For proportionality, it cites only its own case law.
As a matter of ECHR law, it seems like quite a stretch to go from Turkish dresscode cases, which are clearly to some extent unique to Turkey, and a case about headscarves in gym class, to a ban on covering one's face in public. Judging from the ruling, which is as terse as always, it seems like the only way they got there is because they asked whether the law was "manifestly disproprotionate" to the goals pursued. (par. 5) This is a very deferential test, one that may well be more deferential than the "margin of appreciation" that the ECtHR tends to give the High Contracting Parties.
I suppose we shall see what the Strasbourg court will do...
P.S. One of the CDE cases they referred to is my beloved Dwarf Tossing Case! (Which clarifies to what extent human dignity, as an element of public order, is sufficient to justify government intervention.)
UPDATE: Not everybody's a fan.