The Waite Court unanimously ruled in Kilbourn v. Thompson (1881) that the U.S. House improperly investigated and interrogated Hallett Kilbourn regarding a bankrupt real estate venture in Washington D.C., of which the government was a creditor. John Thompson, the sergeant-at-arms of the House, had brought Kilbourn to the House for questioning. When Kilbourn refused to produce documents and answer questions, he was imprisoned in a District of Columbia jail for forty-five days for contempt.

The Court ruled that Congress could not punish Kilbourn because it had conducted an improper investigation into private matters, not future legislation. Chief Justice Waite wrote that “the House of Representatives not only exceeded the limit of its own authority, but assumed a power which could only be properly exercised by another branch of the government, because it was in its nature clearly judicial.”