Academic regalia dates back to the 12th and 13th centuries in Europe. At that time, graduates wore gowns or robes similar to those worn today. However, because each person ordered his own gown, the styles, colors, and materials used in the robes usually depended on the wearer's social status or wealth rather than the degree he was receiving. In the 14th and 15th centuries, the academic hood became a symbol of those receiving doctoral degrees.
The United States created standardized rules for academic regalia in 1895 with the passage of the Intercollegiate Code. These rules were based on the rules developed in Europe in the 14th and 15th centuries. Under the original Intercollegiate Code, colleges and universities recognized three levels of achievement: undergraduate, bachelor's, and master's and doctoral degrees. Distinctions in academic regalia between master's and doctoral degrees were typically made by individual schools, not by the code.
Prior to 1986, the rules for academic Ph.D. regalia required Ph.D. recipients to wear a hood, but did not specify what colors the hood or robe must be. In 1986, however, the American Council on Education specified that Ph.D.s should wear dark blue. The American Council on Education clarified that the dark blue color represented the Ph.D. in general and not philosophy in particular when it stated: "In the case of the Doctor of Philosophy Degree, the dark blue color is used to represent the mastery of the discipline of learning and scholarship in any field that is attested to by the awarding of this degree and is not intended to represent the field of philosophy."
As of 2011, academic gowns for Ph.D.s also feature unique trim, bands on the sleeves, and sleeves cut in a way that distinguishes Ph.D. gowns from those worn by master's or bachelor's degree recipients. For instance, Ph.D. gowns are usually trimmed in black velvet, rather than in a color representing the academic subjects studied. They also have three black velvet bands on the sleeves, which master's and bachelor's gowns do not have. Finally, Ph.D. gowns have full sleeves, instead of the square-cut sleeves worn by master's recipients or the bell sleeves worn by bachelor's recipients.