The photojournalistic tradition of trying not to play a role in the scene you're shooting doesn't answer every ethical dilemma. While the viewing audience of news images would hope that the photographer hasn't intervened or staged the image, does that mean the journalist should simply observe acts of violence and crime? British newspaper The Guardian has spoken to eight photographers who've had to make the decision whether to shoot or act in such situations. Their perspectives (and regrets) are presented alongside a slideshow of the often harrowing images they've taken.