President Donald Trump’s defense hinges largely on arguments made in the impeachment trial of President Andrew Johnson more than 150 years ago: that impeachment requires a crime.

But most legal scholars disagree, including Jonathan Turley, the law professor called by Republicans in the House investigation to argue against impeaching Trump.

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The idea may be attractive to Republicans seeking a legal basis to acquit Trump of having abused his power and obstructing Congress. But legal scholars dispute the idea that the Founding Fathers ever intended for impeachable offenses to require proof of a crime. And historians are equally dubious that the argument from Johnson’s lawyer, Benjamin Robbins Curtis, can be credited with securing Johnson’s narrow acquittal.

“This is a way in which history is weaponized and distorted in order to give these kinds of arguments heft,” said Rachel Shelden, a Penn State University history professor and Civil War-era expert. “It’s a way of trying to promote an understanding of the Johnson impeachment that is false, based on what historians now believe.”

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“I don’t think you can place any weight on that argument for explaining Andrew Johnson’s acquittal,” said Jeffrey Engel, director of Southern Methodist University’s Center for Presidential History and co-author of “Impeachment: An American History.”

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Even if the argument isn’t the best, it may nonetheless be worth making to senators, “who are not judges” and “may be persuaded by arguments that aren’t terribly good law,” said David Stewart, a historian who has written a book about Johnson’s impeachment.

“I’ll be blunt: If I was the president’s lawyer, I’d probably make the argument too,” Stewart said. “But I don’t think it’s very strong.”