Page:United States v. Hansen.pdf/50

18 For example, one does not know from today’s determination whether a noncitizen must actually complete the underlying offense of coming to, entering, or residing in the United States (à la aiding and abetting) or whether completion is not a prerequisite for prosecution (à la solicitation). This sort of uncertainty—the clarification of which, by the way, should be Congress’s policy prerogative—may itself dissuade people from engaging in protected speech. Thus, regardless of whether a potential speaker has the ability, means, and time to track down and interpret this decision (or hire a lawyer to do so) to understand what the law requires, the known unknowns of the majority’s course portend further chill.

The majority attempts to downplay the encouragement provision’s threat to free expression by highlighting that Hansen “fails to identify a single prosecution for ostensibly protected expression in the 70 years since Congress enacted clause (iv)’s immediate predecessor.” But the purported lack of past prosecutions provides no comfort for several reasons.

The first is that we have already said as much—this Court squarely rejected that kind of argument when the Government raised it in a prior overbreadth challenge. In Stevens, the Government vigorously asserted that it had never brought a prosecution implicating the kind of protected expression that the plain text of the statute in question swept in, and that it did not intend to do so. 559 U. S., at 480. The Government “hi[t] this theme hard, invoking