Richard Thompson Ford, a Stanford Law School professor and the author of “Dress Codes: How the Laws of Fashion Made History,” has studied rules and laws related to dress since the Middle Ages.

“Historically, there’s been a really strong norm, both in terms of law and custom, of enforcing a strict division between masculine and feminine attire,” Professor Ford said.

“One of the tricky things is that the norms of gendered dress keep shifting,” he said. “Determining what’s appropriate is always kind of a moving target.” As an example, he cited rules prohibiting women from wearing flapper-style short dresses to work during the 1920s.

“At the time, people said, ‘It’s not feminine, it’s masculine, but also it’s way too sexy,’” Professor Ford added. “But today we’d see that as recognizably feminine.”