President Donald Trump really doesn’t want you to know what’s in his tax returns. During the 2016 campaign, he broke with 40 years of tradition by refusing to make them public. (He insisted they were undergoing a routine audit, which doesn’t mean they can’t be released.) All we know for sure comes from a handful of pages from his 1995 and 2005 tax returns, which raised more questions than they answered. A blockbuster New York Times investigation last fall into Trump’s “tax dodges” suggested his returns could show hundreds of millions of dollars in misclassified income.

But the more Trump hides his returns, the greater the public’s curiosity—and the greater his political opponents’ drive—to see them. Richard Neal, the chairman of the House Ways and Means Committee, formally requested Trump’s tax returns from 2013 to 2018 from the IRS last week. It’s unclear whether the Treasury or the IRS will comply. Mick Mulvaney, the acting White House chief of staff, described the committee’s request as a “political hit job” and said that the president would “never” turn over his tax returns. Instead, the White House appears to be gearing up for a long legal fight. In a four-page letter sent last week, Trump lawyer William S. Consovoy told the Treasury Department’s top lawyer that Congress “cannot legally request—and the IRS cannot legally divulge—this information.”

Here, Trump and his legal team are returning to a familiar legal strategy, one they developed during the 18-month clash over his Muslim travel ban: invoke executive powers in unprecedented or extraordinary ways, use the inevitable defeats in the lower courts to rally his base, and hope that the Supreme Court ultimately sides with him on the merits. It’s worked well for him so far. The only question is whether Chief Justice John Roberts and his colleagues are willing to stomach Trump’s insulting assumption that they will always have his back.

Consovoy’s letter makes a constitutional case for protecting Trump’s returns, drawing from Supreme Court decisions that limited Congress’s power to conduct investigations. In the 1880 case Kilbourn v. Thompson, the Supreme Court blocked the House’s demand for documents related to a private real-estate transaction in D.C. because the dispute was a judicial matter, not a legislative one. And in the 1957 case Watkins v. United States, the justices ruled against the infamous House Un-American Activities Committee when it tried to force a labor organizer to name former Communist Party members without sufficient justification.

Those cases both dealt limits to Congress’ power to subpoena private individuals. In those cases, the court held that there is “no congressional power to expose for the sake of exposure.” But this isn’t exactly analogous to Trump’s situation. He’s the president of the United States, not an ordinary civilian. Congress’ request is directed at the Treasury and the IRS, not him personally. And black-letter law allows congressional committees that draft tax-related laws to acquire any individual’s returns, so long as they keep those returns secret. The statute is clear and unequivocal: