The CIA torture program during the war on terror; the warrantless surveillance of citizens’ communications; the targeted drone strike regime; the barring of Food and Drug Administration regulation of lethal injections; the blocking of an inspector general from telling Congress about the phone call between President Donald Trump and Ukrainian President Volodymyr Zelensky that later led to Mr. Trump’s impeachment.

What do these things have in common? They were all sanctioned in opinions from the Office of Legal Counsel within the Justice Department. The OLC is an institution whose power is far greater than its prominence: Average Americans might not know the office exists, much less that its body of legal interpretation undergirds all manner of executive policy, much less what that body of interpretation says. Many OLC opinions never see the light of day — despite an internal “best practices” memo that advises erring on the side of transparency, barring a need for classification or a valid objection by one of the government entities involved.

Research suggests the office’s supposed preference for transparency is honored more in theory than in practice: A number of previously secret opinions (or in some cases, just their titles) have been wrested into the open by a combination of Freedom of Information Act requests, public pressure and efforts on the OLC’s part to increase access to historical material. Many of these don’t appear to be particularly sensitive to the nation’s security; basically, the OLC’s habit has been to release recent memos when it is inclined to and keep them secret when it isn’t.

Either the executive branch should hold itself to account, or lawmakers should step in. A bill introduced in the 116th Congress would have codified transparency in OLC opinions unless they were classified or had classified information in them, in which case whatever portion was possible should still be released. That determination would be made by the attorney general or a designee, in writing. Other internal reforms could ensure decisions are rigorous rather than reflexive. One idea is to introduce dissenting opinions by OLC staff, giving them power to challenge and, ideally, refine internal decision-making, similar to the military’s use of “red teams”; another is to require that the office independently verify whatever facts form the basis for a presidential request for an OLC decision.

The way the OLC does things may seem inevitable in a sclerotic Washington. But while ordinary citizens may be unaware of how this powerful office operates, they would probably agree on a basic principle: Critical decisions underlying our governance shouldn’t be withheld from the governed.