As scientists heed the call to achieve broader impacts for their work, they will leave their labs and begin to communicate with more diverse, non-expert audiences. To accomplish this, scientists will undoubtedly need help in developing their skills of effective communication. But they also need opportunities to reflect on the roles they may appropriately play in public life, on the responsibilities they are undertaking when they address publics, and on the ideals of good communication to which they are committed. In short, they need help in developing their principles for science communication ethics. Our interdisciplinary team at Iowa State University is developing nine case studies of science communication ethics in order to promote better communication training for STEM graduate students as well as to advance scholarship in the area. In this report, we outline the first three cases, focused on a public statement regarding climate change, on the publication of preliminary but highly policy-relevant results, and on the drafting of a press release for a controversial study.