When the Senate decides this week whether to subpoena documents and witnesses in President Trump’s impeachment trial, it will decide more than just whether former national security adviser John Bolton will give testimony against him — and more even than the future of Trump’s administration. Senators will also be voting on whether to reclaim investigative authority they long ago ceded to the executive branch.

Congress has grown sorely out of practice in conducting its own investigations of presidential misconduct. Since long before Trump, the legislature has become accustomed to waiting for prosecutors to deliver definitive reports rather than doing its own work to gather evidence. The Ukraine case, however, spurred a revival of congressional investigative authority. With no special counsel to turn to, the House of Representatives simply investigated the matter on its own. The question now is whether the Senate will join the House or retreat out of partisan loyalty to the president.

In the early Republic, Congress investigated the executive branch without the involvement of criminal investigators at all. The congressional power to investigate executive branch conduct saw its origins in George Washington’s administration, when a U.S. military force under Gen. Arthur St. Clair was routed by Native American armies in what is now Ohio. The questions were not ones of illegality, but in response to the fiasco, the House took the position that it could serve as the “grand inquest of the nation,” as it was deemed at the Constitutional Convention, and it looked into what had happened. The Washington administration cooperated. Though each branch contested the limits of the other’s authority, this precedent of congressional oversight and executive participation has held ever since.

The idea that the executive branch had a role at all in investigating presidential scandal only began in 1875 with the Whiskey Ring corruption in the Ulysses S. Grant administration. The Whiskey Ring, a network of corrupt distilleries conspiring with federal officials to evade taxes, is the first recognizably modern presidential scandal, complete with a special prosecutor, criminal misconduct in the White House itself, presidential testimony in a criminal proceeding and even the removal of a special counsel for an excess of independence. The Whiskey Ring concluded in several criminal prosecutions, including an unsuccessful one of Grant’s private secretary.