Those of us outside the US think of holidays, sun, Disney, and orange juice when we think of Florida. We don’t even think of it as part of the slavery, blues, and cotton South, and so I was shocked to read in the magnificent, Pulitzer prize winning book, Devil in the Grove: Thurgood Marshall, the Groveland Boys, and the Dawn of a New America, that after the second world war Florida had more lynchings than any other state. I also found it very disturbing how the legal system in the state could be so corrupted, and it’s all come back to me as I read about the acquittal in Florida of George Zimmerman on a charge of murdering the black teenager Trayvon Martin.

Gilbert King’s book tells the story of four black men falsely accused of raping a white woman in Lake County in central Florida in 1948. It’s probable that the white woman wasn’t raped at all, which is why the prosecution never called the doctor who examined her. But the book makes clear that in those times once a black man was accused of raping a white woman then the outcome of the trial was certain whatever the evidence.

Central to the story was that the Lake County sheriff, Willis McCall, was a leader of the local Klu Klux Klan. There were then close links between politicians, those in the criminal justice system, and the Klan.

One of the men accused, knowing what was coming, fled Lake County, but was tracked down by a posse, shot, and killed. White inhabitants of Lake County were ready to lynch two of the others accused, but McCall rescued them, making a promise to the mob that the men would be executed. All three of the accused were badly beaten, as the FBI showed. It was an interesting sideline that the FBI were embarrassed by what was going on in Florida, but were powerless to do much. They could not get the policemen indicted for beating the prisoners.

The accused men were represented by lawyers from the National Association for the Advancement of Coloured People  (NAACP) led by Thurgood Marshall, a highly gifted lawyer who paved the way for other civil rights campaigners like Martin Luther King. Marshall knew that it would be impossible for the men to be found not guilty in a Florida court, and so the strategy of the NAACP lawyers was to gather evidence of injustices in the Florida court and have the verdict overturned in the US Supreme Court.

As expected the men were found guilty, although one was not sentenced to death, which was effectively in Florida an admission that he was innocent. After the first trial the NAACP lawyers were chased out of Florida by the Klu Klux Klan. It took great bravery for a black (and white) lawyer to act on behalf of blacks in Florida’s courts. An NAACP leader in Florida was killed when his house was bombed. Nobody was ever convicted of his murder.

Marshall’s strategy worked, and the Supreme Court overturned the convictions of the two sentenced to death. After this McCall drove two of the prisoners from the prison where they had been held, took them down a quiet road, forced them out, and shot them. One was killed, but the other survived by playing dead. McCall said that he had shot them trying to escape. He was tried by a jury full of his friends and found not guilty.

The remaining prisoner was offered a deal that he would avoid the electric chair if he confessed to the rape. He bravely refused to lie and was retried and again sentenced to death. In 1955 the new governor, concerned by the adverse global publicity about Florida as the state developed its tourist industry, commuted the death sentence to life imprisonment. The prisoner died two years after his eventual release in 1968.

One of the most remarkable parts of this story was that McCall, despite being involved in other similar cases, remained as the sheriff of Lake County until 1972.

The book shocked me both by the extent of entrenched racism in Florida after the second world war and by the complete submission of the legal system to the racism. (My shock is perhaps a reflection of me having a naive belief in the rule of law, and after reading King’s book I read An English Affair: Sex, Class and Power in the Age of Profumo by Rupert Danenport-Hines, which showed clearly how the English legal system was traduced by politicians desperate for a conviction of Stephen Ward in 1963.)

Most blacks in the US, and certainly those in the NAACP, will know of the Groveland Four case and similar cases, and so it’s unsurprising that they are unconvinced by the integrity of the Florida legal system in the Trayvon Martin case.

At the end of the book I thought how remarkable it was that with such recent history the US has a black president, but I think it’s easy to feel Barack Obama’s great discomfort with the present case. The rule of law must be upheld, but is he convinced that justice has been done? I doubt it.

Richard Smith was the editor of the BMJ until 2004 and is director of the United Health Group’s chronic disease initiative.