John Swinney has warned that Westminster must not be able to impose minimum service levels during industrial action in Scotland.
The Deputy First Minister has written to Kevin Hollinrake, the UK enterprise, markets and small business minister, to set out the Scottish Government’s opposition to the legislative proposals.
The controversial plans, which have been dubbed anti-strike legislation, would require minimum levels of service (MSLs) during strikes from ambulance workers, firefighters, rail staff and other essential workers.
Mr Swinney has said the Strikes (Minimum Service Levels) Bill, which is currently making its way through Parliament, would undermine the Scottish Government’s Fair Work principles, while interfering with devolved legislation.
And he criticised the lack of engagement with Scottish ministers before the proposals were presented in Westminster.
In the letter, which was also sent to Scottish Secretary Alister Jack, Mr Swinney said: “It would give UK ministers power to intervene in devolved public services by setting minimum service levels.
“The effect of these regulations on the functions of the Scottish Government and the operation of devolved public bodies is the purpose of the Bill, and is more than incidental.
“We are therefore considering the Bill carefully to assess the need to legislative consent from the Scottish Parliament to its provisions.”
He claimed the law, if passed, would not require the agreement or consultation of the Scottish Government, despite impacting areas directly under the competence of the Scottish Parliament – including health, education, some elements of transport and fire and rescue services.
Mr Swinney added: “It is therefore clear that the UK Government is not in a position to decide either whether there is a need for MSLs for these devolved areas, or what such MSLs should contain.”
He also said the plans risked pouring “fuel on the fire” on a relationship with trade unions which is already at “such a low ebb”.
First Minister Nicola Sturgeon has previously set out her opposition to the proposals, pledging to fight the legislation “every step of the way”.
A UK Government spokesperson said: “Many countries in Europe and around the world who are signatories to the International Labour Organisation have minimum service levels in place covering a range of key services.
“We must keep the public safe, which is why we are introducing minimum service and safety levels across a range of sectors to ensure that lives and livelihoods are not lost.”