As if deciding what to wear to the prom wasn't stressful enough...

The NY Jewish Week is reporting on an increasingly frequent problem in Jewish schools: do they allow their students to bring non-Jewish dates to the prom?

“The core argument on one side is that Jewish day schools should foster the value of Jews marrying other Jews and building Jewish families, and that value should [permeate] the culture of the school, including the prom,” [Marc Kramer, the executive director of the New York-based Ravsak, an umbrella group representing more than 90 Jewish community day schools in North America] said.
“The other argument — equally valid, but wildly different — is that … a policy saying students can only bring Jewish dates to the prom oversteps the boundaries of what a school should dictate”........
Jonathan Sarna, professor of American Jewish history at Brandeis University, said as more intermarried couples send their children to Jewish day schools, some parents are “reluctant to be taught that intermarriage is wrong.”
“[The debate] represents two clashing worldviews in the Jewish community: those who see intermarriage as a challenge and those who see it as an opportunity,” he said.

To make matters more complicated, many kids bring friends to the prom rather than romantic partners.
If a kid ever chose to force the issue, what would be the schools' legal position?