Don’t quote dictum without noting that it’s dictum.
Of all the problems in jurisprudence, one of the trickiest can be distinguishing between a court’s holding and its dictum. It often takes a close inspection of the court’s writing to make that distinction. Essentially, a holding is an appellate court’s determination of a matter of law pivotal to its decision. Anything else said in an opinion is dictum—or, if you’re enumerating instances, dicta (the plural noun).
Although dictum is often dismissed as if it had no value at all, it can be highly persuasive. It may be the best indicator of how the court would decide a case like yours. The higher the court, the more sway its dictum has. So invoking “mere dictum”—as it’s often disparagingly called—from the highest court in your jurisdiction can indeed be persuasive.
But merely noting that a judicial statement you’re quoting is dictum can also give you credibility: you’re not only acknowledging that the statement isn’t binding, you’re also signaling that you’re a meticulous writer. And if you tell your readers in advance what assumptions or different circumstances were at play in the court’s statement, you’re likely to enhance that credibility.
Further reading: For a thorough discussion of the distinction between holdings and dicta, see Bryan A. Garner et al., The Law of Judicial Precedent § 4, at 44–75 (2016).