Sometimes we think we can spot a liar because of the way they behave. It’s encouraging to think that everyone displays signs, or “tells”, that might give them away when they are not speaking the truth.
In the recent plagiarism case against Ed Sheeran, the judge was faced with deciding the veracity of Sheeran’s evidence by comparing what he said at one time against what he said at another and testing both against other known facts or inferences. The judge’s thought process makes for a fascinating read but, in places, I found it thoroughly unconvincing.