Surprise — not: The Pew Research Center offers a summary of a study by a couple of political scientists that found that members of Congress tell the truth only about 25 percent of the time when debating major legislation on the House and Senate floor.

Gary Mucciaroni of Temple University and Paul J. Quirk of the University of British Columbia sought to see how truthful America’s lawmakers were in debating three major bills: welfare reform in 1995-96, the estate tax in 1999-2000 and telecommunication deregulation in 1996.

They meticulously sifted through the Congressional record to identify key claims made by each side to support its own case and to rebut the assertions of its opponents. Then they compared the claims with available data to see if they were true, false or somewhere in between. In all, they examined the accuracy of 18 claims made in 43 separate House and Senate debates.

How did the nation’s lawmakers do?

Not so well. In all, these researchers judged the claims made in only 11 of the 43 debates to have been largely substantiated by the facts. Another 16 were deemed to be “unsubstantiated” — a polite way of saying they were misleading, mostly false or flatly wrong. An additional 16 were judged a politically artful mix of fact and fiction. In all, as reported in their new book, Deliberative Choices: Debating Public Policy in Congress, the researchers rated the quality of the debates somewhere between “fair” and “poor” — a C-, at best.

Does one party tell whoppers more often than the other? It’s hard to tell, Mucciaroni said. “The Republicans performed worse than the Democrats in the welfare reform and estate tax debates, but not as much in telecommunications. We feel that this is probably due to the Republicans controlling Congress, especially the House. We might expect Democrats to do as poorly if they were in control…because majority status emboldens the majority to make more extravagant claims and they feel pressure to deliver ‘results.’”

The researchers stopped short of claiming that members of the House and Senate told deliberate lies to advance their positions. “We don’t pretend to know whether they are lying, are ignorant, or misperceive the facts and informed opinion on an issue,” he said. “Instead of using ‘flatly lying,’ we prefer ‘flatly incorrect’ or ‘flatly inaccurate’.”

We say call a lie a lie and a liar a liar, and be done with it.