Cite as: 558 U. S. ____ (2010) 7 Opinion of the Court an inaccurate estimate potentially subjecting the speaker to criminal sanctions. The First Amendment does not permit laws that force speakers to retain a campaign finance attorney, conduct demographic marketing re search, or seek declaratory rulings before discussing the most salient political issues of our day. Prolix laws chill speech for the same reason that vague laws chill speech: People “of common intelligence must necessarily guess at [the law’s] meaning and differ as to its application.” Con nally v. General Constr. Co., 269 U. S. 385, 391 (1926). The Government may not render a ban on political speech constitutional by carving out a limited exemption through an amorphous regulatory interpretation. We must reject the approach suggested by the amici. Section 441b covers Hillary. B Citizens United next argues that §441b may not be applied to Hillary under the approach taken in WRTL. McConnell decided that §441b(b)(2)’s definition of an “electioneering communication” was facially constitutional insofar as it restricted speech that was “the functional equivalent of express advocacy” for or against a specific candidate. 540 U. S., at 206. WRTL then found an uncon stitutional application of §441b where the speech was not “express advocacy or its functional equivalent.” 551 U. S., at 481 (opinion of ROBERTS, C. J.). As explained by THE CHIEF JUSTICE’s controlling opinion in WRTL, the func tional-equivalent test is objective: “a court should find that [a communication] is the functional equivalent of express advocacy only if [it] is susceptible of no reasonable inter pretation other than as an appeal to vote for or against a specific candidate.” Id., at 469–470. Under this test, Hillary is equivalent to express advo cacy. The movie, in essence, is a feature-length negative advertisement that urges viewers to vote against Senator