After the New York Times published the 1995 tax returns of Donald Trump, Callum Borchers at the Washington Post and others have said it might be illegal. Trump’s lawyer claimed that publishing the returns was illegal without Trump’s consent, and, being Trump's lawyer, he of course threatened “prompt initiation of appropriate legal action.”
Adding to the confusion, during a panel discussion at Harvard Law School in mid-September, Bob Woodward, associate editor of the Washington Post, and Dean Baquet, executive editor of the New York Times, presciently discussed whether they would publish Trump’s tax returns if they got ahold of them. “You know what your lawyers would tell you,” Woodward said, ”if you publish them, you go to jail.” Baquet said he would “seriously fight to publish [Trump’s] tax returns."
For federal tax returns, there is a specific statute that prohibits publishing without consent (26 U.S.C. § 7213(a)(3)). But the Times only published the first page of Trump's New York, New Jersey, and Connecticut tax returns (not the federal tax returns) so that statute would not apply.
Of those states, only New York has a privacy statute that could be construed to apply to non-government employees/contractors like the Times. Not to make your brain atrophy from an overdose of legalese, but the New York statute prohibits
any person who, pursuant to this section, is permitted to inspect any report or return or to whom a copy, an abstract or a portion of any report or return is furnished, or to whom any information contained in any report or return is furnished, to divulge or make known in any manner the amount of income or any particulars set forth or disclosed in any report or return required under this article.
This bit of printed chloroform is a convoluted statute (welcome the study of law), but the fairest reading is that the phrase “pursuant to this section”—i.e., the entire section describing the “general powers of the tax commission”—applies only to those who are “permitted to inspect any report or return” under New York law, such as some government contractors. The other entities listed, such as those “to whom a copy, an abstract or a portion of any return is furnished,” can be anyone, even those who obtained a return not “pursuant to this section.” That includes the Times.
So, let’s assume that what the New York Times did was against the law. A more interesting question is: would that law be constitutional under the First Amendment? After all, prohibiting someone from divulging information to the public is clearly an abridgement of speech, so would the law fall under an exception to the general rule that the government cannot prohibit speech?
The most relevant case would be Bartnicki v. Vopper from 2001. That case dealt with a radio commentator who broadcast a tape of an illegally recorded conversation between a chief union negotiator and a union president. The federal statute at issue prohibited people from “willfully disclosing the contents” of any communication that the person knew or had reason to know “was obtained through an illegal interception.” The Court struck the statute down as unconstitutional because it “implicates the core purposes of the First Amendment" by imposing "sanctions on the publication of truthful information of public concern.” Publishing crucial and truthful information about a presidential candidate a month before the election certainly implicates matters of “public concern.”
Finally, because the New York law makes it illegal to merely “divulge or make known” tax return information, it is broader than laws that prohibit someone from releasing a tax return that he knows (or has reason to know) was obtained illegally. In other words, it prohibits even more speech than the law in Bartnicki. Therefore, it seems likely that the law would be struck down as unconstitutional.