What about the First Amendment? It wouldn’t immunize the original leak, because the government can generally restrict government employees from revealing confidential documents, including tax returns, see U.S. v. Richey (9th Cir. 1991):
[An IRS employee’s] interest as a citizen in commenting upon matters of public concern is … substantial, but it must give way to the government’s interest in this case. … Here, the government seeks to restrict disclosure of private tax information to the press, where the result sought to be accomplished by such disclosure could be accomplished by less deleterious means. Given the compelling governmental interest in maintaining a workable tax system, it is difficult to say that this regulation is unreasonable. See, e.g., Connick v. Myers, 461 U.S. 138, 154 (1983) (government employee’s “limited First Amendment interest” was trumped by action which might “disrupt the office, undermine [supervisor’s] authority, and destroy close working relationships”); Snepp v. United States, 444 U.S. 507, 509 n.3 (1980) (the government’s “compelling interest in protecting both the secrecy of information important to our national security and the appearance of confidentiality so essential to the effective operation of our foreign service” enabled the CIA to “impos[e] reasonable restrictions on employee activities that in other contexts might be protected by the First Amendment”).
(Note that allowing release of such tax return information won’t affect just “certain president[s],” but potentially anyone else who might reasonably worry that an IRS agent would decide that his income or exemptions are of public interest.)
And I suspect that the First Amendment wouldn’t immunize the request for the leak, either. True, abstract advocacy of criminal conduct is almost always constitutionally protected: To fit within the narrow “incitement” exception, it would have to be intended to and likely to persuade people to engage in imminent criminal conduct, which is to say at a specific time in the very near future (minutes, hours or maybe a few days away).
But calls to commit a specific crime are generally not constitutionally protected, see United States v. Williams (2008). “Offers to give or receive what it is unlawful to possess have no social value and thus, like obscenity, enjoy no First Amendment protection.” And while the material we’re discussing here would be unlawful to give rather than to possess, I think the analysis would likely be the same — requests that the listener engage in a specific crime involving a specific person are generally punishable solicitation.
The trouble, of course, is figuring out where the solicitation vs. protected advocacy line is drawn. In Williams, the Supreme Court made clear that it thought there was such a line, and that the speech in that case (“Dad of toddler has ‘good’ pics of her an [sic] me for swap of your toddler pics, or live cam”) was clearly on one side of the line, as solicitation and offer of child pornography. But it didn’t say much beyond distinguishing “a proposal to engage in illegal activity,” which is constitutionally unprotected, “and the abstract advocacy of illegality,” which generally is constitutionally protected. (Consider also Hess v. Indiana (1973), where the court reversed Gregory Hess’s conviction for telling fellow demonstrators who were ordered off a street, “We’ll take the f—ing street later” or “We’ll take the f—ing street again.” The court thought this speech should be judged under the speech-protective test for advocacy and didn’t mention solicitation; maybe that reflects the view that solicitation requires more specificity than in Hess’s statement.)
I think that asking IRS employees — even if not a specific employee — to leak a specific document is likely to be enough to put the statement on the solicitation side of the line, rather than the mere advocacy side. But I can’t be completely certain of that.
Of course, all this is relevant only if the tweet was intended to be serious. If it was just intended to be a joke or hyperbole or otherwise not serious, then it wouldn’t qualify as solicitation, because solicitation is generally defined as asking someone to commit a crime with the purpose of that crime being committed. (That, I take it, was the reason that then-candidate Donald Trump’s “Russia, if you’re listening, I hope you’re able to find the 30,000 emails that are missing; I think you will be rewarded by our press” likely wasn’t seen as a punishable solicitation.) The question isn’t whether the speaker should have known that listeners would perceive the statement as serious, but rather whether the speaker intended that the listeners do so.
Finally, say that someone does send President Trump’s tax return to the New York Times, and this is found to have been prompted by Kristof’s tweet and the tweet is found to have been serious. Would the New York Times be free to publish it? (Note that another subsection of the tax return confidentiality statute bars everyone, and not just IRS employees, from publishing tax return information that “is disclosed [to them] in a manner unauthorized by [federal law].”)
That, too, is not completely clear, but I doubt it. In Bartnicki v. Vopper (2001), the Supreme Court confirmed that speakers have a right to publish information (at least on matters of “public concern”) even if the information was illegally gathered by someone else, and the same would apply to information illegally leaked by someone else. But the court noted that, in that case, “The persons who made the disclosures did not participate in the interception,” though “they did know — or at least had reason to know — that the interception was unlawful.” And the two-justice concurrence elaborated on that:
[T]he broadcasters here engaged in no unlawful activity other than the ultimate publication of the information another had previously obtained. They “neither encouraged nor participated directly or indirectly in the interception.” No one claims that they ordered, counseled, encouraged, or otherwise aided or abetted the interception, the later delivery of the tape by the interceptor to an intermediary, or the tape’s still later delivery by the intermediary to the media. Cf. 18 U.S.C. § 2 (criminalizing aiding and abetting any federal offense).
Soliciting illegal conduct generally counts as a form of participating in the illegal conduct, so I doubt that Bartnicki would provide First Amendment protection for publishing tax return information that was released in response to an unlawful solicitation.
In any event, that’s my quick and tentative sense of the relevant legal rules, such as they are. Naturally, if I am mistaken here, please let me know so I can correct things.