Dariano v. Morgan Hill Unified School District (N.D. Cal.), decided the day before yesterday, upholds a California high school’s decision to forbid students from wearing American flag T-shirts on Cinco de Mayo. (See here and here for more on this case.) On Cinco de Mayo in 2009, a verbal exchange and altercation arose between a group of predominantly white and a group of Mexican students. This altercation involved an exchange of profanities and threats were made. A makeshift American flag was put on one of the trees on campus. A group of Caucasian students began clapping and chanting “USA” as...