To further expand on what
dsc posted, the "Equal Access Act" is a federal law passed by Congress in 1984 to protect student groups in public secondary schools. A school will be covered under the act if:
1) it is a public secondary school;
2) it receives federal financial assistance; and
3) it has a "limited open forum."
A "limited open forum" is created when a school allows any (even just one) noncurriculum-related student group to meet on school premises during noninstructional time. Since your school allowed the "CSA" or Conservative Student Alliance" to form (clearly a "noncurriculum-related" club), my guess would be that your school would meet all three of the above and therefore falls under the "Equal Access Act", as do almost all public high schools (IIRC, there have been at least two public high schools that did not--they banned ALL noncurriculum related clubs and therefore no longer had a "limited open forum". When faced with an either all or none choice, schools have fortunately chosen to allow all.).
{So if the school meets all three conditions above}, the school must allow all such clubs equal access to school facilities, meeting rooms, etc. If a school uses the content of a group's purpose or discussions {as a reason to deny such group equal access}, or simply says that it is opposed to a group organized around a particular topic, it is violating the
Equal Access Act.
In other words, your school's chapter of the GSA should be on safe legal footing.
Good Luck!
And the usual disclaimer: I am not a lawyer and nothing in this post shall be construed as legal advice, either implicit or explicit, blah, blah, blah . . .