Who you shouldn’t use as an expert evidence?

Answer: Albert Einstein and Ernest Rutherford were scientists in physics (also a well defined area of expertise). So their quotes about physics or problem solving might be an expert evidence too. Arnold Schwarzenegger was a pro sportsman once. It is a well defined area of expertise. So his quotes about sports training might be an expert evidence. Daniel Kahneman was awarded with the Nobel Prize for his work on the psychology of judgment and decision-making. Again a well-defined area of expertise. But Mahatma Gandhi was the leader of the Indian independence movement in British-ruled India. “Being a leader” is not a well-defined area of expertise. So his quotes shouldn’t be used as an expert evidence.