The court ruled that the man be released after it emerged that the State had lost crucial evidence and records.
Klaas Lesetja Phakane has been in jail since 2006, after being convicted of the murder of his girlfriend, Matilda Chuence Boshomane.
In the judgment, it emerged that the date of Boshomane's death was unknown.
Her decomposed body was found in a veld and she was last seen on August 19 or 20, 2006 when she and Phakane had an argument.
Because of the state of decomposition of the body, the cause of death could not be determined.
It further emerged in the judgment that Martha Manamela, who was also Phakane's girlfriend at the time, gave police a statement on September 2 that year, in which she claimed Phakane had visited her on August 20.
She claimed Phakane told her that he had a fight with Boshomane and admitted that he had used a waist belt to assault her. She also claimed in the statement that Phakane admitted leaving Boshamane in a veld.
Manamela added that Phakane told her that he had returned to Boshamane's home the following day, but that she was not home. She was also not at the veld where he had left her.
Phakane was eventually arrested and charged with Boshamane's assault and murder. He pleaded not guilty to both charges.
The State's case against Phakane was based on circumstantial evidence and his alleged confession to Manamela.
The trial court later acquitted Phakane of assault, finding that there was insufficient evidence to justify a conviction.
However, he was convicted of the murder charge. Manamela's evidence played a decisive role in the court's decision.
He was sentenced to 20 years' imprisonment.
Phakane appealed his conviction and sentence to a full bench of the high court.
However, the transcript of the trial proceedings did not include Manamela's evidence and the tapes containing her evidence were missing.
Her statement to police was also missing.
The full bench held that the absence of the transcript Manamela's was not such that the court could not fairly determine the appeal.
It went on to dismiss the appeal against conviction but upheld the appeal in respect of sentence.
No longer sufficient evidence
Phakane turned to the Constitutional Court for relief.
His lawyer argued that the absence of the evidence meant that Phakane's appeal could not be determined fairly.
This, he argued, was an infringement of his right to a fair appeal entrenched in the Constitution.
His conviction and sentence should therefore be set aside.
In a majority judgment, the court said Manamela's evidence in court was critical to his conviction by the trial court and, without the transcript of that evidence, the appeal could not be fair.
The court concluded that Phakane's right to a fair appeal had been infringed.
Leave to appeal was granted and the appeal was upheld.
In the circumstances, the court ordered that Phakane be released.
It would be up to the National Prosecuting Authority to decide whether or not to recharge Phakane.
The judgment reasoned that, while there was no longer sufficient evidence to convict Phakane of murder, there was still key evidence from the testimony from Phakane's mother that directly implicated Phakane.