In a recent interview, Hillary Clinton sarcastically asked for China’s help in obtaining Donald Trump’s federal income tax returns. “China, if you’re listening, why don’t you get Trump’s tax returns?” She added: “I’m sure our media would richly reward you.” In so doing, Clinton paraphrased Trump’s shoutout to the Russian government to hack Clinton’s email accounts during the 2016 presidential election (which Russia did).

If the Chinese do not come through, perhaps Congress will. House Ways and Means Committee Chairman Richard Neal, D-Mass., recently invoked a federal law that gives tax-writing committees in Congress a legal right to receive and review any taxpayer’s returns — including the president’s. However, Treasury Secretary Steven Mnuchin has flatly refused to provide Trump’s tax returns, arguing that Neal’s committee lacked any “legitimate legislative purpose” for requesting them.

The relevant statutory language, which dates to 1924, provides that the secretary “shall furnish” the House Ways and Means Committee “with any return or return information” that it requests. The statute’s language is crystal clear — there’s no ambiguity. Moreover, as a matter of constitutional law — and, more specifically, the doctrine of separation of powers — the executive branch does not get to determine what subjects the Congress may choose to investigate incident to its broad legislative powers.

Neal’s committee has now upped the stakes by issuing subpoenas to Mnuchin and Chuck Rettig, commissioner of the Internal Revenue Service, that require submission of the president’s tax returns. If they do not deliver the returns by 5 p.m. Friday, they will almost certainly face contempt of Congress charges.

To date, Neal has invoked only a general legislative interest in federal tax policy as the basis for seeking Trump’s tax returns — potential “legislation relating to IRS examination and enforcement.” However, a much stronger legal basis for the committee’s request exists — and the committee should invoke it now.

Since Trump took office in January 2017, serious allegations have arisen that foreign governments have bought or rented Trump-affiliated properties. If true, these transactions, which Congress has not approved, would arguably violate the emoluments clause — they would literally be unconstitutional gifts (or, more pejoratively, bribes). Violations of the emoluments clause also would provide a strong basis for initiating an impeachment investigation against Trump.

The Constitution prohibits a sitting president from accepting gifts from foreign governments without congressional approval (which Trump has never sought, much less obtained). The emoluments clause prohibits any person “holding any office of profit or trust,” including the president, from accepting “any present, emolument, office, or title, of any kind whatever” from a foreign government or its agents. The clause exists to ensure that the commander in chief puts the national interest first and does not suffer from divided loyalties.

The emoluments clause provides a much stronger legal and constitutional basis for the committee’s request for Trump’s income tax returns than generic concerns about IRS rules or policies. Legislation that requires all presidents to disclose their personal income tax returns — which would fall within the committee’s jurisdiction — would greatly facilitate enforcement of the emoluments clause.

Of course, financial transparency is essential for all presidents. But, in the case of Trump — whose byzantine real estate transactions and hotel operations make figuring out who has been paying him what essentially impossible — it’s imperative. Without access to the president’s balance sheet, which personal income tax returns would provide, the American people simply do not — and cannot — know whether Trump is actually putting “America First” rather than himself.

Remember that the framers greatly feared a chief executive with divided personal loyalties. In addition to the emoluments clause, a second provision of the Constitution requires that any candidate for president must be a “natural born citizen.” (It is perhaps ironic that this is a clause in which President Trump expressed considerable interest during the Obama administration.) The natural born citizen requirement, like the emoluments clause, reflects the framers’ intense fear, bordering on paranoia, of a compromised chief executive who does not put the interests of the United States and its people first.

“We the people” not only need and deserve, but have a constitutional right to a president whose loyalties are undivided. Presidential financial conflicts of interest could affect both domestic and foreign policy in ways that financially benefit the incumbent president — but not the American people. In this sense, then, financial transparency is essential to ensuring that the president is an honest broker (rather than in the financial thrall of a foreign power).

Of course, receiving and reviewing President Trump’s income tax returns will not be the last step in the process of Congress investigating whether the president is advancing the people’s business rather than his own. But, the returns constitute a necessary first step.

In sum, Neal and the House Ways and Means Committee are not, contrary to the administration’s claims, simply engaged in some sort of crass political hit job or partisan fishing expedition. The committee has a legitimate legislative purpose that relates, in a direct and highly credible way, to enforcing the Constitution itself. Chairman Neal should say so — and, if he does, the federal courts are very likely to require Mnuchin to release Trump’s tax returns to the committee.

Ronald J. Krotoszynski Jr. is a law professor at the University of Alabama.