Bill Poser argues that the Supreme Court fails semantics in its decision of Morse et al. v. Frederick. He has two main complaints with the Court's analysis.

The first is that it is unwilling to accept the possibility that the utterance is meaningless.... The other error in the Court's analysis is in mistaking one kind of meaning for another.

While I agree that the Court's semantic analysis is neither profound nor perspicacious, I think Poser has overlooked certain things in the decision that undercut his argument. First, it isn't the case that the Court doesn't accept that the message may be meaningless. This is what Roberts, for the majority, actually writes (emphasis added):

The message on Frederick’s banner is cryptic. It is no doubt offensive to some, perhaps amusing to others. To still others, it probably means nothing at all.... But Principal Morse thought the banner would be interpreted by those viewing it as promoting illegal drug use, and that interpretation is plainly a reasonable one.

In other words, the Court accepts that the message can be viewed as having no meaning, but that's not the point. The majority sees the issue as turning around the actions of the principal, and whether or not she was justified in regarding the sign as expressing a particular point of view. Just because the author of a message intends a particular meaning (or lack of one), it does not follow that the recipients of that message will interpret the message as the author intended. Witness ambiguous headlines like "American ships head to Cuba". In this case, we don't say that the amusing reading is invalid because the author didn't intend it. Similarly, Frederick may well have intended the sign to be nonsense, but that does not bear directly on the question of how others will view it. Poser's second objection makes a fairly strong claim: that the message is, in fact, meaningless because there is no plausible reading as a sentence:

The slogan is in fact meaningless in the sense that it expresses no proposition

He reaches this conclusion through a series of problematic assertions, however. First,

If the slogan is a single syntactic constituent, it must be a Noun Phrase in which "for Jesus" modifies "bong hits".

But why must the slogan be a single syntactic constituent? If it is taken to be an elliptical version of a sentence, then the PP "for Jesus" need not modify the NP "bong hits." It could modify the implied verb. That strikes me as a much more natural reading in context than a single NP "bong hits that are intended to be taken by a person named Jesus" The Court provides two readings that implicitly treat the PP as the modifier of an implied verb:

First, the phrase could be interpreted as an imperative: “[Take] bong hits . . .”—a message equivalent, as Morse explained in her declaration, to “smoke marijuana” or “use an illegal drug.” Alternatively, the phrase could be viewed as celebrating drug use—“bong hits [are a good thing],” or “[we take] bong hits”—and we discern no meaningful distinction between celebrating illegal drug use in the midst of fellow students and outright advocacy or promotion.

I'm not sure, therefore, how Poser can object that, "the banner does not, on any plausible analysis, contain the kind of syntactic structure that serves to express propositions, namely a sentence, not even a sentence part of which is not overt." In a strict sense, the first reading is not propositional, since a proposition has a truth value, and imperatives, like questions, don't actually have truth values. Yet an imperative does imply advocacy of a position, if we read the statement literally. And at the very least it does provide a sentential interpretation. So the decision is innocent of the two mistakes that Poser accuses it of committing. I agree with Poser that the reasoning is weak, but I have a different view of where the problem lies. What is missing from the Court's analysis is any account of what function "for Jesus" plays in the statement. That phrase is conspicuously absent from the quotation above. There are several things to note in this regard. If Frederick's banner had simply read "BONG HiTS", we would clearly be entitled to infer that it advocated smoking marijuana. The common understanding of the act of holding up a sign is one of advocacy of the thing named. When a person stands on a street corner with a banner simply reading "USA", we interpret that act as one of support or celebration of the USA. It is not taken to mean disapproval ("the USA is bad") or mere reference ("this is the USA"). So if we are to understand "bong hits for Jesus" as a single NP (which, mind you is suggested by Poser, not the Court), then we would still interpret the phrase as advocacy, even if it's unclear exactly what sort of bong hits we're talking about. On the other hand, if we take "for Jesus" to modify an implied verb, e.g., "take bong hits in order to show your support for Jesus," advocacy is still implied, because, as I noted when the case was originally argued, the expression is a snowclone in the pattern X for Jesus, where X represents some group, activity, or object representing an activity whose purpose is to strengthen belief in Christianity. In other words, at its core this is an advocacy snowclone, and I strongly suspect that both the principal and the Court grasped this fact intuitively, even if they were unable to explain themselves articulately. And yet, there's another aspect to the slogan that I'm surprised Frederick or his lawyers didn't argue. By dropping a phrase of the drug culture into a template associated with evangelical Christianity, the incongruity is so striking that it's clearly intended as satirical. After all, to read the slogan as serious advocacy, you have to assume it means something to the effect of "take bong hits to show your belief in Jesus." And while some religions do involve taking certain drugs as part of worship, evangelical Christianity has never been one to do so. So rather than arguing that the banner was meaningless, which allowed the Court to conclude that it had meaning for others regardless, Frederick might have been better off arguing that the incongruity clearly marks it as satirical speech, and that no reasonable person could perceive it as anything other than satirical. In short, I think the banner does advocate something on one level, but that advocacy is immediately undercut by the satire. In other words, the banner advocates drug use exactly as much as Swift advocates cannibalism in "A Modest Proposal."