One of the many advantages of Judge Brett Kavanaugh's long service on the D.C. Circuit is that we have a very clear picture of how he applies the First Amendment to statutes that restrict speech.
The D.C. Circuit hears many campaign finance cases, and the Institute for Free Speech reviewed them, starting with Emily's List v. FEC:
His opinion in Emily’s List is particularly impressive. Foreshadowing later rulings in Citizens United and SpeechNow, Judge Kavanaugh clearly articulated a First Amendment right for associations to spend money in support of candidates. The opinion demonstrates an ability to anticipate trends in First Amendment jurisprudence before they fully take hold. . . .
Emily’s List v. Federal Election Commission dealt with a spate of regulations that the FEC put in place against certain nonprofit corporations in the aftermath of the 2004 presidential election. Specifically, in response to the so-called “527” expenditures made during the 2004 election against President Bush and Senator Kerry, the FEC imposed a panoply of limits designed to treat nonprofit corporations, functionally, as if they were political parties.
In an opinion that preceded and foreshadowed the Citizens United and SpeechNow.org opinions, Judge Kavanaugh wrote an opinion for the Court reversing the lower court and striking down these regulations on First Amendment grounds. The Court decided that nonprofits such as Emily’s List, a pro-choice, partisan nonprofit dedicated to electing pro-choice Democratic female candidates for office, ought to have “the right to spend unlimited money to support their preferred candidates” and “receive full First Amendment protection.” 581 F.3d at 8-9. “A non-profit that makes expenditures to support federal candidates,” Judge Kavanaugh wrote, “does not suddenly forfeit its First Amendment rights when it decides also to make direct contributions to candidates.” Instead, so long as it complied with modest regulation, it was “entitled” to make certain “advertisements, get-out-the-vote efforts, and voter registration drives” out of an “account…not subject to source and amount limits.” Id. at 12.
Nevertheless, Judge Kavanaugh warned that government could easily overstep in this area. He noted that the ruling did not decide whether Congress could constitutionally extend the ban to lawful permanent residents, nor did it decide whether Congress could prohibit foreign nationals from engaging in political speech other than contributions. He also cautioned the government “that seeking criminal penalties for violations… will require proof of the defendant’s knowledge of the law.”