They urged the new body to come clean about the public money being paid out in response to complaints of police errors, by regularly publishing all future compensation payouts.
The Sunday Herald has had to use Freedom of Information legislation to establish that £70,000 was paid by police in 34 successful claims of wrongful arrest between 2008 and 2012. These payments are never normally disclosed and crucial details of the cases remain secret.
Margo Macdonald, Independent MSP for Lothians, said: "It would be an excellent statement of intention and a defining statement as regards the attitude of the new single force if it said it would consider regularly publishing all compensation payments.
"The important thing is it is open and accessible to the general public. That way we'll see how much money is involved, what sort of wrongful arrest it was and what sort of misdemeanours were committed."
Scottish Liberal Democrat justice spokesperson Alison McInnes MSP said: "Even though the number of claims for wrongful arrest remains relatively small, I would like to see the figures published regularly as a matter of course. Having anonymised information on the circumstances, each wrongful arrest made public would serve as a helpful tool to identify any repeated failings."
On Monday the country's eight previous police forces became a single body, Police Scotland, in what some have called the biggest change in Scottish policing in living memory and the most significant public service reform since devolution.
On the eve of the new force's launch, Patrick Harvie, MSP for Glasgow and justice spokesperson for the Scottish Greens, said: "Transparency in the operation of our police service is of paramount importance.
"By being clear about mistakes we can have confidence that efforts will be made to prevent such errors.
"It is important we are able to hold our police service to account and I would urge the new single force to consider what measures could be introduced to maintain public trust."
Lewis Macdonald MSP, Labour's Shadow Cabinet Secretary for Justice, said fear of compensation claims should not deter officers from making arrests, but added: "It is vital that any allegations of wrongful arrest and imprisonment are investigated fully." He called on cases of officer incompetence or corruption to be dealt with "swiftly and without fear or favour".
Prominent Scottish lawyers including Tony Kelly, Cameron Fyfe and Aamer Anwar made similar calls, arguing there was no argument for keeping payments "hushed up".
Human rights lawyers and campaigners believe the present police complaints system favours the police, is hidden from public scrutiny, and denies justice to hundreds of victims of wrongful arrest.
Scots detained without any legal basis are being advised not to pursue compensation because the high burden of proof makes police "virtually immune" from being sued.
Since 2008, 719 complaints of unlawful or unnecessary arrest have been made against Scottish police, but just three have resulted in misconduct proceedings – a success rate of 0.4%.
Human rights lawyer Aamer Anwar believes the current system for dealing with wrongful arrest is a "toothless tiger" that puts off potential victims.
"Wrongful arrests do take place, it's a reality. But when people ask me 'what can I do about this now? Can I take action against the police?' by and large the answer is usually no," he said. "If you happen to be poor, if you happen to have previous criminal convictions, then it's unlikely that some people will take your complaint seriously.''
V ICTIMS of wrongful arrest can pursue justice through the police complaints procedures and by suing the force for compensation.
Wrongful arrest and detention occurs when there are insufficient legal grounds for police action.
Some 56% of the 719 wrongful arrest complaints officially lodged with Scottish police forces since 2008 were dismissed because they were "unsubstantiated by available evidence", according to figures from the Police Complaints Commissioner for Scotland (PCCS). The success rate of 0.4% in triggering misconduct proceedings is lower than every other category of complaint except assault.
Tony Kelly, a leading Scottish lawyer and visiting professor in human rights at the University of Strathclyde, called the figures "hardly inspiring". "It is a product of the way that the police work. If there is factual dispute, somebody has got to get over the hurdle of being believed," he said.
Paul McLaughlin, of the Scottish charity the Miscarriages of Justice Organisation, said: "If it's police investigating police then it cannot be fit for purpose. How can it be trusted? That's the problem. If it's a structural problem within the forces which creates a culture that leads to wrongful arrest - that's a major concern to us."
Lawyers say as many as 1000 Scots are wrongfully arrested and detained each year, yet just a fraction of them receive compensation.
Cameron Fyfe, one of Scotland's top civil lawyers, said the police were virtually immune from being sued for wrongful arrest. He now advises victims not to pursue recompense unless they can prove officers acted with malice.
Changes to complaints procedures came into force last week. The Police Complaints Commissioner for Scotland has been given extra powers to investigate the most serious incidents involving officers and was renamed the Police Investigations and Review Commissioner (PIRC). The body is still headed by Professor John McNeill.
Neil Richardson, Deputy Chief Constable of Police Scotland, pointed out that Scottish police detain or arrest more than 200,000 people a year, and the number of wrongful arrest complaints received is very small by comparison.
He said: "As with any aspect of the reform of policing, we will always look at ways of improving and standardising our work and if there are ways we can do things better or more effectively, then we will seek those opportunities.
He added: "There are no plans to change the current processes around the way the police manage compensation payments."