These shirts are usually worn by seminarians, deacons, priests, bishops and religious brothers. Unless there is a rule in the diocese or the religious community, they can be of any color and style.
The roman collar is not a universal uniform. In the northern countries of Europe, such as Germany, Netherlands and several others, it came into use after Vatican II. Clerics and Brothers wore cassocks, habits or suits and ties. In the lower European countries such as Spain and Italy, they wore cassocks, habits or crew neck shirt (usually black) with a blazer.
In Mexico they still may not wear any distinctive clothing on the streets.
For many years in the original 13 US States, they were not allowed to wear anything but a black shirt with white collar, but it was not the square cut that is so common today. It was completely white all the way around. The Council of Baltimore under the direction of the first Catholic bishop in the USA, Bishop John Carroll (Sp?) wanted clerics and religious to blend in with the Anglican clergy when in public to show support for the New Nation. I’m not sure in what year the rule was changed or if it was simply forgotten.
In many places, because of climate, religious men will wear a light colored “clerical” shirt instead of the habit of their order. The mendicant and the monastic habits tend to be quite warm, especially the Franciscans, Carmelites, and Benedictines because they are very dark colors and have long sleeves with yards of fabric. The lightweight colored shirt with the tab is more practical and healthier, especially if the religious is a priest who has to wear alb and vestments over it.
JR
