I have seen clergy peregrinos in soutanes / cassocks walking the Camino across Spain. Typically, these fellows are in a group. Working at the Pilgrim Office, I have also seen them on queue with the arriving pilgrims.
I do not have knowledge of the practice in France. But, as others have said, I cannot imagine there being a law against it.
Just as an aside, and because someone above touched on it, head coverings and those coverings that obscure one's face, are proscribed in several European countries. But, these laws dates back to the 1970s and 1980s when various Western-European countries were having problems with terrorist organizations that liked to rob banks, kidnap people for ransom or political reasons and to stage attacks across Europe. Examples include, but are not limited to, the Red Brigades, Black Hand, ETA, etc.
While some may point to current issues regarding recent arrivals from the middle East and Africa (no moderators, I will NOT go further), the fact is that most of these head covering restrictions have antecedents that stretch back some 35 or more years. These laws are primarily intended to permit law enforcement to identify potential criminal and terrorist suspects, contributing to the general safety of the population. Contrary to some opinion, they are NOT intended to restrict the practice of religion. This said, I cannot speak to more recently implemented rules. I do believe that the French and Italian laws pre-date current geopolitical issues.
Hope this helps the dialog.
