"Distribution of harmful matter to minors." The law requires a warning that says it shouldn't be sold to minors. Instead, they put on a sticker with a snarky remark about how some people might find the contents objectionable, "but life is like that" (something like that). So kids were buying the album and parents were freaking out when they found the poster hanging in their bedrooms.

There was never really any notion about being charged with obscenity. Most people reject that out of hand anyway. The issue was that there is a law that attempts to ensure parents get some warning so they could decide if some materials may not be appropriate for their kids. The matter before the jury was to decide if that poster was that kind of material, and if the snarky sticker was sufficient warning.