Amid concerns about crime and public safety, at least two major U.S. cities recently considered banning ski masks or balaclavas to prevent criminal behavior, despite a lack of academic research about the effectiveness of such bans.
Last month, Philadelphia became the latest city to enact a ban in some public spaces, including parks, schools, day care centers, city-owned buildings and public transit.
The ban comes with exceptions for working in cold weather, religious expression and activities such as protesting and playing winter sports.
