The legal basis of any claim you may have against a doctor or hospital is likely to be in the civil law of negligence. Negligence law is from that part of the law that lawyers call common law, that is to say, it is not to be found in an Act of Parliament but in the decisions of judges over many years. Negligence is a part of the civil law called "tort" law. A tort is an act or omission that causes harm to an individual.
In order to bring a negligence claim against a doctor you must prove all of the elements that form the tort of negligence. This is crucial. You will probably hear your lawyer call these issues: breach of duty; causation and loss (or quantum). Each case must be analysed in a strict manner and each of these issues addressed before you can be advised if you have a claim. If one of the elements can’t be proved then there is either no case or one with such a small financial value that we would advise against starting legal proceedings. No two cases are exactly the same. Some are strong on the issue of breach of duty but have a weak causation argument. In that sort of case it might be thought that it was straightforward to prove that a negligent error had been made but difficult to prove what was the consequence of that error.
Negligence cases are never easy. One cannot use hindsight to judge the quality of care. The person bringing the claim must prove all of the allegations that are made. Only very rarely is it up to the person being sued to disprove the case against them.
A doctor owes a duty of care to his or her patient. If the doctor fails to care properly for their patient they are said to be in Breach of Duty. The law on this issue is to be found in a 1957 case called Bolam -v- Frien Barnet General Hospital. That case is authority that a doctor is not liable in negligence if he or she has acted in accordence with the practice accepted as proper by a responsible body of medical opinion. This means that if a doctor is able to call evidence that a particular practice would be supported by a body of medical opinion that a case could be successfull defended. This is usually called a "Bolam defence" and is a common problem to people bringing Clinical Negligence claims. These days a judge is can, in some circumstances, look behind the medical evidence that is being presented and consider if a certain practice or opinion is logical in the face of medical and scientific knowledge.
If it is possible to identify a part of the medical care that is thought to be negligent, it is then necessary to prove that the act (or just as often a failure to act) is either the cause or a material contribution to cause of the injury. This issue is sometime more difficult to prove than breach of duty as it involves the expert witnesses having to speculate about what might of happened. Often it is possible to find scientific and statistical evidence to back up an opinion, sometimes however this is a problem if there is little or no research on an issue.
Clinical Negligence cases rely very heavily on the experts witnesses that each side calls to Court. The medical issues involved in a case are proved by calling independent specialist doctors, called expert witnesses, to court so that they can be questioned by lawyers representing the patient and, usually, the NHS Trust. A judge will then decide whose evidence is preferred and that party wins the case.