Andrew Wakefield, the doctor who first suggested a link between the MMR vaccine and autism acted unethically, the General Medical Council (GMC) has found.
Dr Wakefield's 1998 Lancet study caused many parents to refuse the vaccine, leading to a rise in the number of measles cases. His findings were later discredited.
The GMC focused on his research methods, rather than the truth of his claim, and found that he had acted "dishonestly and irresponsibly".
The verdict criticised invasive tests that he carried out on children, including spinal taps, without having the relevant qualifications. He also paid children at his son's birthday party £5 each in return for blood samples.
Wakefield, who now lives and works in the US, said: "The allegations against me and my colleagues are unfounded and unjust and I invite anyone to examine the contents of these proceedings and come to their own conclusions."
The hearings have lasted for two and a half years. This is one of the longest hearings in the regulator's history.