The question at hand is whether Juul intentionally marketed nicotine to people below 18.
There's pretty strong circumstantial evidence that they did. Building relationships w teenage social media influencers is part of that.
The unfortunate fact is that Juul achieved explosive popularity among high schoolers. It spearheaded a U turn in youth nicotine use rates, which had been declining for a long time and are now way up.
The investigation is here to determine to what extent this was the result of a deliberate strategy.