Guest: Mark Siegler, M.D., Professor of Medicine and Surgery at the University of Chicago.

The forebears of today's doctors could have only dreamed of the modern medical technology commonly in use today. But even as these tools have generated ethical challenges as fast as they simplify physical ones. When do we start and stop treatment? How do we decide whether we are doing more harm than good? Today on Focus, we're joined by Dr. Mark Siegler to discuss ethics in today's medicine.