Dr Navin Zala, 62, carried on as a GP despite facing at least nine different complaints, a series of police investigations, and four criminal trials ? none of which ended in a conviction.
He was finally struck off after an NHS trust reinvestigated the complaints. A tribunal has upheld the decision.
In a 57-page report, the tribunal panel criticised police, prosecutors and health officials for mistakes which contributed to the delay in stopping Dr Zala from working.
Doctors and patients' groups said the disclosure that the GP was allowed to continue for so many years raised serious concerns about the system of regulating doctors' conduct.
Dr Zala was found to have abused six female patients ? four of them while they were pregnant ? by carrying out inappropriate breast examinations and unnecessary internal examinations at his practice in Gravesend, Kent between 1988 and 2007.
In two cases, women who went to him complaining of sore throats were asked to lift up their tops while he examined their breasts.
The patients, all young women, were "carefully selected so as to avoid confrontation, complaint and detection", the tribunal found.
It concluded: "The findings reveal a pattern of behaviour by Dr Zala towards each of these women that was abusive, exploitative and sexually motivated over a period of many years."
A female GP who worked nearby, and who helped one of the victims to make a complaint, claimed Dr Zala had been able to carry on working because other GPs failed to act on allegations they heard against him.
She said: "There was a sort of an old boys' club where if a woman complained about the way she was being treated by a male doctor she was seen as crazy. There were certainly missed opportunities [to stop him].
"I don't think he thought he was doing anything wrong. That's the other awful thing about it. He thought what he was doing was acceptable."
Katherine Murphy, chief executive of the Patients Association, said: "This case raises serious concerns. Alongside other
recent cases it highlights the need for strong and robust regulation of doctors."
Dr Zala, who lives in Gravesend with his wife, Helen, started working as a GP in the area in the early 1980s after qualifying in Poona, India, in 1975.
The first complaint against him was made in 1992, by a woman who claimed he had examined her inappropriately. Three more women then came forward with complaints about incidents dating back as far as 1988.
One said that when she went to him about a sore throat, he insisted on examining her breasts "while you are here".
Dr Zala stood trial at Maidstone Crown Court in 1994 on eight counts of indecent assault against three women.
Following a retrial, he was acquitted of all charges - in part because it emerged that NHS officials had arranged a meeting between two victims prior to them contacting the police, thus "contaminating" the evidence.
The same year, another female patient accused Dr Zala of touching her breasts and stroking her leg while she was pregnant, leaving her feeling "like she had been raped".
He appeared before magistrates and was committed for a crown court trial, but it never took place.
Later in the 1990s, Dr Zala stood trial again over new allegations from another female patient, but was again cleared.
Then, in 2007, a woman known as SC accused Dr Zala of touching her breasts inappropriately when she went to visit him with a lump in her caesarean scar.
Shortly afterwards, two more women came forward with historic allegations against the GP, and police were informed.
One of the women, PP, claimed that when she had gone to see Dr Zala with a headache as a teenager in the late 1980s, he had stood behind her and "pressed himself into her", while on another occasion when she had abdominal pains he had "cupped her breasts".
In evidence, she said: "I can recall going home and hiding in my room. I was only a child but I felt dirty. I wish I had spoken up at the time but I was just a teenager ? who would believe me over a respected doctor?"
The other woman, KS, alleged that when she saw Dr Zala in 1991 with a sore throat, he had "lifted up her top and touched her breast".
Dr Zala was arrested in Jan 2008, but was told seven months later that no action would be taken against him.
The decision to drop the case was taken after police discovered KS and SC had discussed their allegations prior to coming forward, creating a risk that their evidence could not be relied upon in court.
Despite the lack of any criminal convictions, West Kent Primary Care Trust (PCT) removed Dr Zala from its "performers list" in May 2009, meaning he could no longer work as a GP in the area. A tribunal has now upheld the decision.
Dr Zala has also been removed from the national performers list, meaning he cannot work as an NHS GP anywhere in the UK. He is due to face a General Medical Council (GMC) "fitness to practice" panel.
The tribunal report criticised the failure of police and the Crown Prosecution Service to bring criminal charges over SC's complaint in 2007.
It found that "on the balance of probabilities" the allegations of SC and PP were proved, as were earlier allegations brought by four other women.
The report said: "The natural instinct of most of these patients was that they did not want to believe that their doctor had abused their trust.
"Many of the women were pregnant. Many of the women were vulnerable.
"We had little doubt that [the doctor's] method was to carefully select the women on whom he performed 'examinations' in a superficially quasi-medical manner so as to avoid confrontation, complaint and detection. His actions were sexually motivated."
Criticising the failure of authorities to act sooner, the tribunal report says: "The lack of confidence that nearly all these patients prospectively felt about complaining to anyone in authority does not ring at all hollow when one considers what actually happened on those occasions when the concerns of some patients were brought to the attention of other health professionals, the Health Authority, the local medical committee, the police, and the GMC."
Dr Zala declined to comment.
A spokeswoman for the GMC said: "When we received concerns about [his] practise in 2007 we immediately referred these to the police.
The police concluded their investigation with no further action, at which point we continued with our own inquiries.
"We cannot discuss investigations that have not resulted in action on a doctors' registration."
A spokeswoman for West Kent PCT said: "In 2007 we received some serious complaints about the conduct of the doctor. As soon as the PCT received the complaints it suspended [Dr Zala] and immediately started a major investigation and was able to successfully remove him from its performers list."