How did this case get to the Supreme Court?

Because nothing gets the square's knickers in a bunch like flaunting marijuana use.  

Well, that's a very -- I find that a very, a very disturbing argument, because schools have and they can defined their educational mission so broadly that they can suppress all sorts of political speech and speech expressing fundamental values of the students, under the banner of, of -- of getting rid of speech that's inconsistent with educational missions.

The Ninth Circuit decision can be found here (PDF). The briefs I could find are the petitioner-school board here (PDF) and the respondent-student here.

The first thing that becomes clear is that there is no agreement on the facts of the case. This disagreement is at the heart of the dispute and, I believe one of the reasons this case has made it so far. The other reason is that the Ninth Circuit decision has some important implications for the doctrine of qualified immunity.

The Ninth Circuit opinion refers to the event (which was the passing of the Olympic Torch) as "partially supervised by the school". Respondent claims that the event was not a school event at all. Petitioner claims that the event was a "school activity." Unfortunately, the Ninth Circuit got the case on appeal from the summary judgement of the district court, so the facts were never really nailed down.

The Supreme Court (which is reviewing the Ninth Circuit's decision) will be stuck with this:

One amicus...argues that we should analyze this not as a student speech case, but simply as speech on a public sidewalk. Were this factually such a case, the law would be easy indeed, but the facts established by the submissions on summary judgment make this a student speech case. Even though Frederick never got to school that morning, that was only because he got stuck in his driveway because of the snow. School had started and the students were released to watch the Olympic torch pass. And even though supervision of most students was minimal or nonexistent, the school could have supervised them more if it chose to, as it did with the gym class and perhaps the pep band and cheerleaders. Frederick was a student, and school was in session.

There are three main precedents that the Court will have to deal with. First, under Tinker v. Des Moines Independent Community School District, high school students' First Amendment rights are only restricted if the student speech "substantially interferes with the work of the school or impinges on the rights of other students." Here, petitioner argues that the pro-drug message is substantial interference. Respondent argues that there was no disruption or interference caused by the sign, which wasn't even chosen for its pro-drug message. Petitioner also draws attention to the fact that the students involved specifically chose an inflamatory sign for display exactly when the nationally broadcasting TV crew came by.

Telling that Bush thinks it means something and thar the religious right is agin' him.

this means that, though the student placed himself in the area where the officially sanctioned other students were located, he himself couldn't possibly be part of it.

i posit that, for the school to argue otherwise, negates their own stated rules and regulations. you can't have it both ways, only when it's for the convenience of the school. what they should have done was punish him for his unexcused absence, not unfurling the banner.

is it absolutely required that you be an idiot to be a high school principal in the U.S., or only a secondary consideration in employment?