Mr Salmond will go to the Court of Session seeking a judicial review of the Scottish Government’s procedures on handling complaints of sexual misconduct against current and former ministers.
The former SNP leader condemned the process, the outcome of which remains unknown, as “unjust” and claimed it had not allowed him to present his case.
“The procedure as put into operation by the permanent secretary is grossly unfair and therefore inevitably will lead to prejudicial outcomes,” Mr Salmond said.
Nicola Sturgeon said the Scottish Government would “vigorously defend” its processes, and Leslie Evans, the permanent secretary at the Scottish Government, said Mr Salmond’s statement contained “significant inaccuracies which will be addressed in those court proceedings”.
Rules for dealing with complaints by government ministers were only introduced in December, following an internal review prompted by the wave of high-profile harassment claims against politicians, including the former SNP minister Mark McDonald, last year.
Dr Nick McKerrell, a law lecturer at Glasgow Caledonian University, said judicial review of employment practices was “extremely rare… not least because the bill for such legal actions is very expensive and usually exceeds £50,000.
“For most people like you or I, the courts are not an option when it comes to challenging an internal complaints process. As well as the expense, the court would usually expect these matters to be resolved in-house or use an employment tribunal.
“The Scottish Government is different because it is a public body of the highest level and can fall under a different jurisdiction. The few cases of judicial review involving employment law issues previously brought to the Court of Session have tended to involve senior personnel within the NHS or local authorities who have lost their job.”
Dr McKerrell added: “In this kind of review, the judge is not being asked to consider whether the outcome of any investigation is right or wrong. They are being asked to rule on whether the decision has been arrived at fairly and if it is legal.
“The outcome of a judicial review into internal process would have absolutely no bearing on how police would investigate any allegations of criminal action which are reported to them.”
Andrew Tickell, a lecturer in law at Glasgow Caledonian University, also pointed out that “whether or not the Scottish Government investigation was fair and lawful is entirely distinct” from any criminal investigation that may take place into Mr Salmond’s conduct.
James Chalmers, the regius professor of law at Glasgow Caledonian University, suggested that the most Mr Salmond might achieve through his legal challenge is to “blur the distinction in the public eye between the important question of whether the allegations are true and the less important question of whether the procedures were correct”.
Mr Chalmers added: “It’s a gamble that might make things worse for him because the court could very quickly say, ‘Go away’.”
Mr Salmond withdrew a separate legal bid seeking to block the Scottish Government from revealing the two allegations against him after the Daily Record published the information.