George Washington University Law professor Jonathan Turley, a frequent defender of Donald Trump who also advocated for the ex-president as a witness during his first impeachment, just received a lesson of his own after attacking President Joe Biden’s great grandfather. Turley, a Fox News legal pundit who predicted Trump would lose his claim that he can’t be prosecuted for election crimes because of “presidential immunity,” wrote a new article in which he outlines “a recent discovery of the criminal history of the great-great-grandfather” of Biden. “It turns out that the evasion of accountabili…