Inspired by Sudha's post yesterday, I did a little research into the legal status of male field hockey players.
Here in Massachusetts, boys who want to play on existing girls teams have a state constitutional right to do so. In 1979, the Supreme Judicial Court struck down MIAA's former policy that forbid boys from playing on girls' teams but allowed girls to play on a boys' team if there was no girls team in that sport. Under the state equal protection clause, a blanket exclusion of boys is unconstitutional.
But Massachusetts, along with a few other state and local jurisdictions, provides more protection for male field hockey players than what Title IX requires. Title IX allows exclusion on the basis of sex in all contact sports. In noncontact sports, exclusion is allowed only if a counterpart team is offered for the underrepresented sex. So, if field hockey is a contact sport, excluding boys is permissible under the statute, but determining whether a sport is contact sport can be a tricky threshold question. Title IX regulations define contact sports as "boxing, wrestling, rugby, ice hockey, football, basketball, and other sports the purpose or major activity of which involves bodily contact." 34 CFR 106.41(b). The Third Circuit once considered whether field hockey involved bodily contact as a major activity and found there was enough factually evidence of contact to reverse the district court's classification of it as a noncontact sport as a matter of law. See, e.g., Williams v. Bethlehem School District.
But the limits Title IX places on a boy's right to play field hockey doesn't turn on its classification as a contact sport so much as it does on whether he is a member of an underrepresented sex. This is because courts have not read "underrepresented" to mean "underrepresented in this particular sport" but rather "underrepresented in athletic opportunities overall." In the Williams case described above, the court decided that even though male athletes at the plaintiff's school were underrepresented in field hockey, they dominated the athletic opportunities overall. Thus, the school could exclude boys from the field hockey team (regardless of whether a trial court ultimately determined that field hockey is not a contact sport). Other courts have followed that lead. This law review article by Adam Darowkski has a good summary of the caselaw.