In April, Rep. Richard Neal (D-MA), who chairs the House Ways and Means Committee, sent a letter to the IRS formally requesting Trump’s federal income tax returns going back to 2013.

Neal claimed that Congress “has a duty to conduct oversight of departments and officials,” and in this case, that duty involves evaluating the IRS policy to audit all presidents’ tax returns. The letter cites a 1924 law that gives the House Ways and Means Committee the power to request tax returns from the Treasury Department for review in closed session.

But on Monday, Treasury Secretary Steven Mnuchin officially denied Democrats’ request. “I am informing you now that the Department may not lawfully fulfill the Committee’s request,” Mnuchin wrote in a one-page letter to Neal. Mnuchin cited concerns about violations of privacy as the primary reason for the denial.

Presidential candidates are not required by law to release tax returns, but every major-party nominee in modern American history has done so — until Donald Trump. Trump’s refusal to adhere to this norm has set up a massive legal fight between Congress and the White House.

So where does this leave us? Does Congress actually have the right to demand Trump’s tax returns? And now that the Treasury Department has refused to hand them over, what happens next?

To get some answers, I reached out to 11 legal experts. Their full responses, edited for clarity and length, are below.

Jessica Levinson, law professor, Loyola Law School

I expect the justices of the Supreme Court may well be the ones to answer the question. A reading of the plain language of the tax code indicates that Congress does in fact have the legal authority to request and obtain tax information from any filer, including the president. Therefore, if Steven Mnuchin, the secretary of the Treasury, refuses Congress’s request, he would be violating the law.

But the president of the United States is, of course, not just any tax filer. And the Supreme Court will be careful about separation of powers issues that ask whether a congressional committee can force the Department of Treasury to hand over the president’s tax returns.

The president’s lawyer has claimed that Congress must but does not have a “legitimate legislative purpose.” Congressman Neal, the chair of the House Ways and Means Committee, has provided such a purpose. Neal claims he is investigating the effectiveness of the IRS’s policy of auditing the tax returns of sitting presidents — although that doesn’t quite explain why he is requesting returns including years both before Trump became president and during his presidency.

That members of Congress may obtain President Trump’s tax returns does not mean that they will automatically, or ever, become public. Under the tax code, the congressional committee which requests the tax returns can only review them in a “closed executive session.”

Andy Grewal, law professor, University of Iowa

Let’s suppose that one of the congressional tax committees is chaired by a racist person. And let’s suppose that he demands that the IRS give him the tax returns of various civil rights leaders, so he can harass them on account of their race or politics. Under one commonly expressed view, the IRS is helpless here. The statute says the IRS “shall furnish” tax returns to the committee chair upon request and that’s the end of it.

But there’s another view: The Constitution applies to Congress. The Supreme Court has repeatedly told us that the Constitution permits Congress to perform investigations and subpoena documents only when it pursues a legitimate legislative purpose. If that standard applies here, the IRS can deny the request. Pursuing invidious racial discrimination is not a legitimate purpose.

Of course, regarding the request for President Trump’s returns, there is not even a hint of racial animosity. So the facts are quite different. But the request presents the same threshold legal question: Does Rep. Neal need a legitimate legislative purpose? In my view, that answer is clearly yes.

It will be much easier to show a legitimate legislative purpose for a request about the president’s tax returns than for civil rights leaders’ returns. But in either case, we should recognize that constitutional standards apply.

Daniel Shaviro, law professor, New York University

This is not an issue on which there is any possibility of reasonable disagreement. Any well-informed person who disagrees either that the Ways and Means Committee has an obligation to demand Trump’s tax returns as part of fulfilling its oversight duties or that Trump is legally obliged to turn them over is either a partisan hack or contemptuous of the rule of law.

Trump has credibly been accused of engaging in criminal activity for decades. It’s undisputed that he is still profiting from his businesses. There is substantial information in the public record suggesting that he is for sale (or subject to blackmail) and that many of his public policy decisions have been made for corrupt reasons. The tax returns may help provide information that sheds light on his motives. It’s an indispensable part of congressional oversight, and Republicans as well as Democrats in the Congress ought to recognize this (and in private probably do, whether or not they care).

All this is even leaving aside the law that would be quite clear in favor of the request even if all of the above evidence of criminality, corruption, and improper motives were not so powerful.

It’s obvious that business tax returns as well as individual ones are a necessary part of the oversight here. I don’t know why the particular ones were selected, and I would think that casting the net far more broadly (e.g., all Trump businesses, and all tax returns for the last 20 years) would have been well within reasonable oversight.

Leandra Lederman, law professor, Indiana University

As chairman of the House Ways and Means Committee, Rep. Neal absolutely has the power to request the president’s tax returns and returns of his businesses.

The Internal Revenue Code contains a lengthy section that generally protects the confidentiality of tax returns/return information and prohibits their disclosure by government employees. The provision Rep. Neal is using is a specific statutory exception from that disclosure prohibition. That exception says that the secretary of the Treasury (or his delegate) “shall furnish” the chairman of the Ways and Means Committee with any tax return or return information requested in writing.

Note that this does not entail public disclosure of the returns — under this exception, any return or return information that identifies a particular taxpayer must be provided to the “committee only when sitting in closed executive session” unless the taxpayer in question consents in writing.

Rep. Neal made a written request, as the statute requires. The statute itself does not say that a justification for the request is necessary. However, Rep. Neal also included in his letter a statement that the House Ways and Means “Committee is considering legislative proposals and conducting oversight related to our Federal tax laws, including, but not limited to, the extent to which the IRS audits and enforces the Federal tax laws against a President.” This is a legitimate concern, as the history of former President Nixon’s initially lenient IRS audit illustrates.

Rep. Neal’s letter requests returns and return information for a six-year period beginning in 2013. Several of these years precede President Trump’s presidency. However, those tax returns may have been under IRS audit after President Trump was elected or took office. And regardless, in determining “the extent to which the IRS audits and enforces the Federal tax laws against a President,” it should be helpful to compare the period before and during President Trump’s presidency.

Rep. Neal’s letter was addressed to the commissioner of the IRS. It is not up to President Trump to respond. If the IRS and Treasury do not turn over the requested returns and return information to Rep. Neal, presumably Rep. Neal will sue for enforcement of the statute.

Philip Hackney, law professor, University of Pittsburgh

The statute provides that if the Ways and Means Committee chairman makes a written request, “the Secretary shall furnish such committee with any return or return information specified.” Chairman Neal made a written request specifying certain returns of President Trump. The IRS has an obligation to turn over the returns. Congress made tax returns private by statute but provided commonsense exceptions such as allowing a state agency a path to access returns when need is shown. It also made an exception for specific committees of Congress without regard to any need. It is appropriately using that exception in this instance.

Trump attorneys suggest the request emanates from impermissible animus and is therefore constitutionally suspect. They suggest Congress must have a legislative need and that this is lacking. While Congress could surely not use the authority in a way that would discriminate on the basis of race, there is no showing of any such discrimination here.

But if the Treasury Department refuses to hand over the returns, the chairman might consider holding the commissioner of the IRS and perhaps the secretary of the Treasury in contempt of Congress. The committee might then file a declaratory judgment asking the DC District Court to hold those officers in contempt and provide an injunction ordering them to comply with the law.

Though the law seems clear, it’s hard to know what will happen. Strikes me [that] the worst outcome would be for the Supreme Court to find the matter a political question, and in effect allow the executive to flout the law to protect himself.

Francine Lipman, law professor, University of Nevada Las Vegas

Congress has enacted specific laws regarding the confidentiality of tax returns and related information. The general rule is that these materials are confidential and cannot be disclosed. This sweeping protection should give all tax return-filing individuals comfort that their tax returns and related information are protected from disclosure under federal law.

However, like most general rules, there are exceptions that are necessary for the administration of federal (and state) tax systems as well as for other critical issues, most notably criminal matters.

One of several exceptions is that upon written request from the chairperson of the House Ways and Means Committee, the Senate Finance Committee, or the Joint Committee on Taxation, the secretary of the Treasury “shall” provide any requested returns or return information. The one stated qualifier to this release is that if the tax return or related information directly or indirectly identifies a taxpayer, then the secretary “shall” provide the materials in a closed executive session (unless the taxpayer consents to the disclosure).

Thus, under federal law, Rep. Richard Neal or Sen. Chuck Grassley (R-IA) — chair of the Senate Finance Committee — can make a written request for the president’s tax returns and return information and Steven Mnuchin, secretary of the Treasury, “shall” provide them, albeit in a closed executive session.

If the secretary of the Treasury does not provide the materials requested in accordance with federal law, the issue will likely be decided by a US district court. This would be a case of first impression, and eventually, the court most likely will decide that the tax returns and return information “shall” be released. However, litigation over this matter certainly will delay this much-anticipated release.

George Yin, law professor, University of Virginia

Chairman Neal’s request is on firm legal ground. A law enacted in 1924 authorizes him to request anyone’s tax return information and provides that the secretary of the Treasury “shall furnish” the information requested. It doesn’t contain any basis for the secretary to refuse.

The background behind the law supports this broad interpretation of Congress’s authority. Prior to 1924, the president had the sole and unconditional right to obtain and disclose anyone’s tax return information. Congress was frustrated by this law because its investigations of executive branch officials and agencies (including the tax agency) required examination of tax return information. Since only the president could release the information, Congress actually had to seek permission from the president to carry out investigations of the executive branch. Congress decided that as a co-equal branch of government, it had to have the same access to tax information as the president at the time.

If there is a refusal and the matter ends up in court, the disagreement may be resolved based on whether the request furthers a constitutional responsibility of Congress. Neal’s request identified Congress’s two main responsibilities — its lawmaking and oversight functions.

Rebecca Kysar, law professor, Fordham University

The House Ways and Means Committee’s request to obtain the president’s tax returns falls squarely within its oversight and legislative authority, and Treasury Secretary Mnuchin has no basis to refuse the request.

The chairman of the Committee, Rep. Neal, is relying upon Section 6103(f), which entitles Congress’s tax committees to obtain any tax return or other tax information, including IRS audit work files. Under Section 6103(f), the Treasury secretary “shall furnish” these documents upon written request from the committee, denying any exercise of discretion from the secretary.

Even if Section 6103 were not on the books, Congress’s inherent legislative powers under Article I of the Constitution would support this request. Courts have ruled that Congress can investigate issues to aid in its consideration of legislation, administration of existing laws, and general oversight authority. To be sure, these powers are limited somewhat: Congress can only investigate matters on which it has power to oversee, legislate, or fulfill some other legislative function. Since all of Congress’s actions need to be within its constitutional authority, this general constitutional limitation on Congress’s investigatory powers likely extends to 6103(f) investigations.

But here, there are clear legislative purposes that Neal is seeking to fulfill in making the request. In his letter to the IRS commissioner, Neal predominantly grounds his request in oversight authority of the IRS, assessing whether the agency is fulfilling its duty to enforce the laws fairly against President Trump and whether to revise the laws relating to presidential tax duties.

Trump’s lawyer has already argued that Neal’s stated reasons are politically motivated. He points to the fact that Neal has not asked for the returns of prior presidents. Yet the committee could reasonably base the need for new legislation on presidential audits on the experience of one president alone, especially one whose possible tax improprieties have already been publicized.

Additionally, Trump’s sprawling business empire presents unprecedented and unforeseen challenges to the audit process that now may justify statutory revisions for similar situations in the future. Trump also claimed to be under audit when he took office, and Congress can legitimately seek to determine how the agency pursued those audits after he took office.

Ari Glogower, law professor, Ohio State University

Rep. Richard Neal’s request from the IRS of President Trump’s tax returns and related information is a lawful exercise of the House Committee on Ways and Means’ investigative authority.

In his letter to Treasury objecting to the request, President Trump’s lawyer William S. Consovoy cited the 1957 case of Watkins v. US, which considered intrusive investigations by the House Un-American Activities Committee (HUAC) in a prior era.

Watkins is not helpful for President Trump. The case contemplates even broader congressional investigative power than Rep. Neal needs to justify his request. And unlike the HUAC in Watkins, Ways and Means is acting with a legitimate congressional purpose and within its clear jurisdictional authority. This purpose may include investigating whether we need new laws to ensure that the IRS enforces the president’s obligations to pay taxes.

Section 6103(f) of the Internal Revenue Code in turn provides a formal procedure for Congress to exercise this constitutional authority and removes these requests from the shield of tax return privacy.

Of course, this process would have unfolded differently if President Trump had followed his predecessors and voluntarily released his returns. Different justifications explain Rep. Neal’s legal request and the voluntary disclosure norm for presidential nominees. It could be, however, that Rep. Neal’s legal reasons to request this information overlap with the reasons President Trump would prefer to keep it private.

Ilya Somin, law professor, George Mason University

Congressional Democrats have good reason to seek the disclosure of President Trump’s tax returns. For decades, previous presidents disclosed voluntarily in order to allow Congress and the public to scrutinize them for evidence of possible wrongdoing and conflicts of interest. Trump’s worldwide network of business interests gives rise to unusually severe risks in the latter regard.

But the law the Democrats are relying on has the potential for serious abuses of power.

The Democrats may be on sound legal ground in using a 1924 law requiring the IRS to disclose any tax return upon the “written request” of the chair of one of several congressional committees. But the very existence of that law is frightening. Congress could potentially start using it to go after other people — including private citizens and political activists who cross one of the major political parties, or influential members of the relevant congressional committees. The law may have been largely moribund for years. But the current controversy could change that. Norms against its abuse can easily fray, just as other political norms have.

The law only allows the committee to consider the returns in “closed executive session,” if the information within could identify the taxpayer. But, as David French points out, it is not difficult for Congress to circumvent this rule by using leaks. It could also pressure the IRS to audit the individuals in question.

A high percentage of Americans who pay income taxes have likely violated hyper-complicated federal tax laws at some point or other. The threat of subjecting tax returns to detailed congressional or IRS scrutiny could well deter many from engaging in speech or political activism that might attract the ire of Congress.

To prevent such skullduggery, the law should be changed to require disclosure of the tax returns of presidents and perhaps other high officials, but deny Congress the power to scrutinize all tax returns at will.

Ciara Torres-Spelliscy, law professor, Stetson University

The question of whether the chairman of the House Ways and Means Committee can lawfully request President Trump’s tax returns from the IRS turns on a history lesson of the Teapot Dome scandal and its aftermath. The Teapot Dome scandal involved the leasing of oil fields by Secretary of the Interior Albert B. Fall and alleged bribery under the Harding administration in the 1920s.

The Teapot Dome scandal inspired a few federal reforms which are relevant to today’s events with the Trump administration. One of the reforms Congress passed in response to the scandal was the Federal Corrupt Practices Act of 1925, which expanded federal campaign finance disclosure requirements and included expenditure caps for congressional candidates. Another reform was the Revenue Act of 1924, which provided the ability of chair of the House Ways and Means and the chair of the Senate Finance Committee to demand tax returns from the IRS.

So what can we learn from this history? First, campaign finance reforms are one way that Congress can respond to restore faith in the government after a corruption scandal. Second, the Supreme Court has recognized Congress’s power to compel testimony so that it can do its job of informed legislating. And third, the chairman of the Ways and Means Committee is well within his statutory rights today under the Revenue Act of 1924 to get his hands on the president’s tax returns as well as the tax returns of his businesses.