As of today there are 162 cases alleging miscarriages of justice on the books of the Scottish Criminal Cases Review Commission. Some may be guilty and are trying work the system in their bid for freedom. But others are innocent people languishing behind bars - and that is a serious indictment of the Scottish police and our courts.

Derek Ogg QC, a leading defence lawyer, is clear about why the innocent are being sent to prison. Our justice system, under-funded and under pressure, is weighted towards miscarriages. It is in the culture of our police and our courts. Ogg can speak without fear of contradiction; he has years of experience fighting some of the hardest cases to come to trial.

"The main problem is targeting by police. They don't have enough officers so when they arrive at a crime scene, the first thing they do is look at their books and see who has form for a similar offence. They then make the evidence of the crime scene fit their suspect, rather than finding suspects from evidence at the crime scene.

"If they get statements from witnesses that don't point towards their suspect, they often don't send these to the Procurator Fiscal. So when the fiscal prepares the case, they've no idea there are people out there who contradict the case being built against the accused.

"Then we have legal aid. The legal aid board boasts about cutting its budget but what that means is defence lawyers like me can't afford to find experts to re-examine evidence. We can't get independent pathology or forensic reports. And I've had cases where clients would have gone to jail if I hadn't been able to find independent experts.

"The prosecution is also supposed to disclose everything they know about a case to the defence. Most do, but take it from me, there are some who don't. And that can mean that evidence which proves a person didn't carry out a crime is never heard in court. If that happens you have an innocent person going to jail.

"It was always the first tenet of Scots law that it was better nine guilty men walked free than one innocent one go to jail. That has changed. If we want a society that is just we have to face up to the failings in our system and change them. The bottom line is that the police have to start doing their job properly, so we can all sleep in our beds peacefully without thinking that we've put innocent people behind bars and the real criminals are still out there."

CASE 1: Stuart Gair

After the best part of 12 years in jail, Stuart Gair will finally get his day in court on September 27. Gair, who was jailed for life for the murder of Peter Smith in Glasgow city centre, has perhaps the most compelling proof, of any of the prisoners who claim they were wrongly convicted, that he is the victim of a miscarriage of justice.

At the end of this month, he will appear in court in Edinburgh for the first sitting of his appeal. On the same day he will apply for interim liberation, asking the court to bail him pending the outcome of the appeal process. September 27 will be a dark day for the Scottish legal establishment. Gair's appeal makes ugly reading for the establishment, particularly the top brass at Strathclyde police and the Crown Office.

During the appeal, Gair's legal team will show that the knife which Gair was supposed to use to kill Peter Smith could not have inflicted the fatal wound. It is forensically impossible that Smith was killed with the knife linked to Gair. But that is the least of the Crown's worries. The real worry for the police and the prosecution is that the key witnesses at the original trial who linked Gair to the murder have now retracted their evidence, claiming they perjured themselves on the stand because they had been threatened and intimidated by police.

Smith was a homosexual who was killed in Glasgow's gay red light area - near the St Vincent Street toilets. Most of the men who claimed Gair was seen near the murder spot were gay. They claim police threatened to out them, and beat and verbally humiliated some of them, to force them to lie about Gair. Chief among these men is William McLeod. He was charged with the murder himself, prompted by detectives to name Gair as the killer and reduced to tears during interrogation, with officers telling him: "Just name anybody." The murder charge against him was dropped, but he was arrested for perjury after saying in court he didn't know Gair. After a night in police cells he returned to court and incriminated Gair. The perjury charge was dropped. Since the trial, McLeod, filled with remorse, has tried to kill himself.

An alibi for Gair will also be brought forward at the appeal. Hector Wood, who knew nothing of Gair until the night of the murder, met Gair at a B&B in Glasgow the night Smith died. The pair watched TV that night, and Wood's affidavit shows there is no way Gair could have killed Smith. Even more damning are Wood's claims that police threatened him to change his story. At the time, Wood had an outstanding fine against him and police told him "We can make it disappear for you" if he said he had not been with Gair at the time of the murder. Wood refused and he was arrested for the outstanding fine and sent to jail. Wood was never called to give evidence at court. Today, even Smith's family want to see Gair freed, believing he was framed by police. They also want an investigation into police corruption in the case and charges brought against investigating officers for perverting the course of justice if evidence proves they fitted up Gair.

"Even though my appeal is coming up I can't be positive about my future," Gair said from his cell in Shotts Prison. "You live in hope for the first three years, thinking someone will say 'sorry, we got it wrong'. After the hope fades you just get numb. I just focus on fighting for my freedom. I'm scared to hope I will be freed, in case the appeal fails. The dashing of my hopes again would destroy me. My imprisonment is an indictment of Scotland. The men who jailed me represent law and order. The police and the Crown were happy to see an innocent man jailed."

CASE 2: Andrew Smith

Nobody serves 22 years for culpable homicide. Some convicted of the offence get off with as little as probation and most serve around five to seven years for the crime. Of course, Smith and his defence team are fighting the case on the grounds that a struggle ensued between Smith and Cunningham, and the dead man fell and struck his head in a clear case of self-defence. "What this letter amounts to," says Smith, from the house in Angus where he is now living with his girlfriend while on bail waiting appeal, "is the Crown admitting that I served 22 years in jail for absolutely nothing. A statement of this magnitude has never been made before, yet I have waited for almost a year for my appeal to be called. The Crown knows I'm innocent yet they keep me hanging on in this torment. It's inhumane. I know I'm innocent but I can't shake off the fear that they could still take me back to jail at any time."

Smith is represented by the same lawyer who is acting for Stuart Gair, Glasgow solicitor John Macaulay. In both cases Macaulay is staggered by the failings of the police, the courts and appeals system.

"With Gair's case the whole story just stinks of police malpractice. We have to have a serious inquiry into the conduct of investigating officers," he said. "With Smith we have the Crown admitting he is innocent of the crime he is convicted of. But we have to think about what happens to these men when they are freed. They have lost years of their lives and become institutionalised. How will they cope? No successful appeal can fix the destruction that's been wrought on their lives."

Tommy Campbell & Joe Steele

TC Campbell has never made any bones about the fact he was a wild man in his youth. He was a criminal, but we wasn't a murderer. Campbell and Steele are serving life for the deaths of six members of the Doyle family during Glasgow's infamous ice cream wars. In effect, their 1984 conviction made them mass murderers.

The men have claimed from the outset that a key witness, William Love, lied to the High Court after being coerced by the authorities into making a vital statement against them. Love himself has repeatedly stated he lied. But all that was to no avail. In 1998, after being freed on bail in 1997 pending appeal, they were sent back to prison when their attempt to have the conviction quashed failed. Their's was one of the first cases to then go before the Scottish Criminal Cases Review Commission (SCCRC), an independent body set up in 1999 to examine miscarriages of justice, and granted the power to refer cases to the Court of Appeal.

At the end of last month, the SCCRC had to take the Crown Office to court to fight for the right to have access to sensitive papers relating to the case. Lord Clarke ruled the Crown had to hand over all its papers to the SCCRC as it had been granted full investigative powers by parliament and had to act with independence. The SCCRC has also reviewed documents held by Strathclyde police and found material not previously produced by the Crown. Campbell told the Sunday Herald by phone from Shotts Prison that the papers proved he had been framed.

In the Campbell case, it is not just TC who is serving a life sentence for a crime he apparently didn't commit. His young wife, Karen and his two-year-old daughter Shannon, born while Campbell was on bail, are also victims. Running out of money, isolated and living in Barlanark, one of Glasgow's toughest schemes, Karen said: "I see Tommy once a week with Shannon in prison. We fell in love when Tommy was on bail and nobody ever imagined he would go back to jail.

"Now I'm alone in a flat with a young child who thinks everyone's daddy lives behind bars. The corruption in this case has two extra victims - me and Shannon. If there was an ounce of humanity in the courts they would admit they were wrong and free my husband. But then humanity isn't really an issue for the police and prosecutors."

The Others

Ashbury, from Ayrshire, was jailed in 1997 for murdering 51-year-old Marion Ross. New fingerprint analysis has cast doubt over whether crime scene prints linked to him were actually those of the dead woman. During the same case the police officer, Shirley McKie, was charged with perjury. She had denied a print in the dead woman's house was hers. McKie's name was later cleared.

On Friday, Brian Donnelly, who was serving life for murdering Glasgow prostitute Margo Lafferty, had his sentence quashed at the Appeal Court in Edinburgh on the grounds that the original trial judge, Lord Dawson, misdirected the jury and the conviction was unsafe. He could face a new prosecution as the Crown was granted leave to bring a new trial within two months.

Donnelly was originally found guilty by a majority verdict despite his defence naming a convicted sex offender as a potential killer. He admitted having sex with the woman on his 19th birthday but denied murder.