Dr Andrew Wakefield, the doctor who first suggested a link between the MMR vaccine and autism, has been struck off the medical register.
It is a significant decision amid the long-standing controversy over the jab.
What is MMR?
MMR is a combined vaccine against measles, mumps and rubella, three common infectious diseases of childhood.
It was introduced in the UK in 1988 to replace single vaccines for each disease.
It is used in countries throughout the world, with millions of doses delivered each year.
Why were people worried about it?
In 1998, a study published in the respected journal The Lancet raised the possibility that the jab may be linked to autism and bowel disease.
The paper and the media furore that followed it prompted many parents to decide against having their children vaccinated with the three-in-one jab.
No direct link between MMR and autism yet found in the body
Studies of vaccinated and unvaccinated children show no difference in autism rates between the two
Some opted to have their children vaccinated using single vaccines for each disease. However, others decided against having their children vaccinated against these diseases at all.
Mumps, measles and rubella are all serious diseases, particularly measles which can be fatal. Many doctors were concerned that a drop in vaccination levels could leave many children at risk.
What do other experts say?
The UK government and the vast majority of scientists insist that the three-in-one jab is safe.
Complications of measles
1 in 2,500-5,000: Death
1 in 100: Hospital admission
1 in 1,000: Meningitis
No research has been published to back up claims that it may be linked to autism and bowel disease.
There have been many studies examining the safety of MMR since 1998. All have concluded that the three-in-one jab is safe.
Last year The Lancet, which published the controversial MMR paper in the first place, publicly announced it should never have printed it.
It says the study was flawed and that Dr Andrew Wakefield, the lead author, had a serious conflict of interest.
Dr Wakefield insists he has done nothing wrong and that the science behind his study is still valid.
What was the General Medical Council hearing about?
It is easy to forget that the hearing was not about whether MMR is safe. Instead, it was about the professional conduct of Dr Wakefield and two of his colleagues.
Complications of mumps
1 in 25: Deafness - usually with partial or complete recovery
1 in 30: Pancreatitis Hospital admission
Mumps during pregnancy can cause miscarriage
The GMC disciplinary panel examined whether the doctors failed to get proper ethical approval for their research, and then carried out procedures on children that had not been sanctioned by the ethics committee.
The General Medical Council found Dr Andrew Wakefield guilty of serious professional misconduct over the way he carried out his controversial research.
It follows a GMC ruling earlier this year that he had acted unethically.
Dr Wakefield, who now lives in the US, denies any wrongdoing.