'Covering doctors' standing in for unavailable colleagues: What is the legal position?

Covering doctors are those who stand in for colleagues when the latter are unable to deal with their patients. Covering doctors who begin to issue telephonic instructions to nurses or other healthcare practitioners regarding the treatment of the patients they are covering are in the same position as any other doctors treating patients. They cannot argue that the patients they are covering only become their patients once an emergency or crisis occurs or when they see the patients for the first time, and that prior to that their function is merely to monitor the patient's progress. They also cannot rely on telephone instructions for long periods of time when the patient's health may be in danger, without seeing the patient. However, if covering doctors are found to be negligent they can still escape liability if the plaintiff cannot prove a causal link between their negligence and the harm that resulted 'beyond a reasonable doubt'.