Republicans in the House hoping to rain down subpoenas on the Biden administration over everything from the president’s handling of classified documents to Hunter Biden’s laptop have gotten a reality check from the Justice Department: if it’s part of an “active investigation,” you won’t get much out of us.

In a lengthy letter to James Jordan, the Ohio Republican who now heads the House’s Judiciary Committee, the Justice Department’s Carlos Uriarte said the department stands ready to cooperate with the panel as it sets out to exercise its oversight responsibilities, but only to a point.

“Consistent with longstanding policy and practice, any oversight requests must be weighed against the Department’s interests in protecting the integrity of its work,” the letter, first obtained by Politico, said. “Longstanding Department policy prevents us from confirming or denying the existence of pending investigations in response to congressional requests or providing non-public information about our investigations.”

A MAGA-friendly conservative, Mr. Jordan has signaled that he intends to steer the Judiciary committee down a path that will include investigations into a number of issues involving the FBI, the Drug Enforcement Agency, the Bureau of Alcohol, Tobacco and Firearms, as well as the Justice Department itself.

While some of these inquiries may not involve ongoing investigations by the department, the most contentious ones — over handling of classified documents by both Presidents Biden and Trump, allegations of wrongdoing by Mr. Biden’s son, Hunter, January 6, and Mr. Trump’s efforts to undermine the 2020 election — all fall into the category of “active investigations” and are likely to get the cold shoulder from the Justice Department.

Last month, for example, Attorney General Garland said his investigation into the riot at the Capitol on January 6, 2021 was “far from over,” despite 950 arrests, 484 plea agreements, and 192 jail sentences so far for those involved. Additionally, special prosecutors have been named in the classified documents cases and the inquiry into Mr. Trump’s election interference, both of which have only recently started working on their cases in earnest. All these cases will undoubtedly be considered ongoing investigations by the Justice Department.

The U.S. Attorney’s office in Delaware also reportedly has an ongoing investigation into Hunter Biden and is weighing charges for tax crimes and making false statements related to a gun purchase. The investigation phase of the cases could be wrapped up by this summer, but if charges are filed and the case goes to trial it would still be considered an active investigation until a verdict is reached or some sort of plea arrangement is made.

The Justice Department’s letter also would appear to put a damper on a subcommittee formally established last week by Mr. Jordan to investigate the so-called “weaponization” of the federal government during the January 6 investigation and the Covid pandemic. The subcommittee unilaterally gave itself the right to investigate “ongoing criminal investigations,” but the Justice Department letter would appear to pour cold water on that notion.

Both the Judiciary committee staff and Mr. Jordan himself tweeted last week that the White House letter is part of an effort to stonewall their investigations, but the Justice Department letter cited precedent going back at least as far as President Reagan’s term for the executive branch to withhold information from Congress in certain circumstances.

“This policy with respect to Executive Branch investigations was first expressed by President Washington and has been reaffirmed by or on behalf of most of our Presidents, including Presidents Jefferson, Jackson, Lincoln, Theodore Roosevelt, Franklin Roosevelt, and Eisenhower,” the head of Mr. Reagan’s Office of Legal Counsel, Charles Cooper wrote in a 1986 memo to Attorney General Meese. “No President, to our knowledge, has departed from this position affirming the confidentiality and privileged nature of open law enforcement files.”