Breach of Duty

Negligence has a specific legal definition.  In the medical context, negligence means treatment or care which falls below medically acceptable standards.  In other words, care which at the time in question no competent or responsible medical practitioner in the relevant field of medicine would have given.  Treatment or care which is unusual or unconventional is not negligent if there is a reputable body (albeit small) of medical opinion which approves it.  If a doctor is rude or indifferent, that in itself is not negligence.

Causation

It is not enough to simply prove that the care was negligent.  You also have to prove that the negligent care has caused identifiable injury and loss.  There are cases in which the patient can prove that the doctor was negligent, but even had the best care been given, this would not have made any difference because, for example, there was insufficient time for appropriate care to have an effect.  This may arise (for example) in delayed diagnosis of cancer or birth injury cases.  There are other cases in which an entirely different cause for the injury is found, which is unrelated to the negligence.  For example, the accident that caused the injury that led to medical treatment.

A patient who cannot prove both that the care was negligent and that the identified negligence caused the injury will not win his/her case.

The burden of proving the case is on the patient.  It is not sufficient to put the case on the basis of “I was fit before I went into hospital and now I am not, so they must have done something wrong” or “the doctor was negligent so he has to prove that he did not injure me”.

The standard of proof is what the lawyers call “balance of probabilities”, thus a patient has to prove that it is more likely than not (that there is a better than 50% chance) that the negligent care caused the injury.