Coming to a stranger's rescue: physician involvement at the scene of an emergency.

On a Saturday evening last November, two well-known Los Angeles physicians who came to the aid of a cardiac-arrest victim in a Palm Springs hotel were arrested for interfering with an emergency medical rescue and resisting arrest. The incident triggered a shock wave that was felt throughout the California medical community and far beyond. Just what is the relationship between physicians and paramedics in such a situation? Who is authorized to take charge, and who is most qualified?