Pope Francis’s inauguration mass in Rome today was a good opportunity to observe one of the intricacies of papal etiquette, namely what is known as le privilège du blanc (the privilege of white).
Women are generally expected to wear black in the presence of the Pope, although not all follow this guideline (for instance, Queen Margrethe wore grey last time she visited the Vatican). But since an unknown date there has been an exception made for the wives of Catholic kings, who have been allowed to wear white in the Pope’s presence.
In former days, this included the Empress of Austria-Hungary as well as the queens of France, Spain, Portugal, Italy, Bavaria, Belgium and Poland (but apparently not the Queen of Saxony, probably because the country did not share the royal family’s Catholic faith), but after the disapperance of most European monarchies the privilege of white today extends only to the Queens of Belgium and Spain, the Grand Duchess of Luxembourg and female captains regent (i.e. heads of state) of San Marino.
Other female members of royal families (except Italian princesses, I believe) and Catholic wives of Protestant monarchs (such as Máxima of the Netherlands will be when her husband ascends the Dutch throne on 30 April) do not have the privilege, which also does not extend to the wives of sovereign princes. Or at least it did not do so until recently.
While her mother-in-law, Princess Grace, always wore black when meeting popes, Princess Charlène of Monaco wore white when she and Sovereign Prince Albert II were received in an audience by Pope Benedict XVI on 12 January this year. The Vatican Press Office subsequently stated that “in accordance with prescribed ceremonial of the Vatican for Catholic sovereigns, the princess was allowed to dress in white”.
However, Princess Charlène wore black at the inauguration today, and the Princess of Liechtenstein was not present, so it seems unclear whether the privilege has really been extended to the wives of Catholic sovereign princes. The Queen of Spain was also absent, but the Queen of the Belgians and the Grand Duchess of Luxembourg both wore white.
However, it might also be noted that there have been occasions when ladies enjoying the le privilège du blanc have chosen not to make use of it, the most recent example I can think of being the late Grand Duchess Joséphine-Charlotte of Luxembourg, who wore black the last time she and Grand Duke Jean were received by Pope John Paul II before the Grand Duke’s abdication in 2000.