In a letter to Deputy First Minister John Swinney, Alister Jack warned that the United Nations Convention on the Rights of the Child (Incorporation) (Scotland) Bill, which was backed unanimously by MSPs, would infringe on the ability of the UK Government to pass laws in Scotland.
A similar concern was raised about the European Charter of Local Self-Government (Incorporation) (Scotland) Bill, put forward by independent MSP Andy Wightman and also passed unanimously this week.
Before the passage of the UNCRC Bill, Mr Jack wrote to the Deputy First Minister, asking for changes to ensure it did not apply to legislation passed by the UK Government or UK ministers, but no such amendments were tabled.
The act ensures all public bodies operating in Scotland have to consider children’s rights in all of their actions.
Scotland became the first country in the UK and one of only a few nations around the world to pass the landmark legislation.
Mr Jack said he would use the four-week period from the passage of a Bill in Holyrood until it receives royal assent to decide whether it should be blocked or referred to the Supreme Court.
He admitted that the UK Government and the Scottish Government have “different views”, but he would do all that he could to “respect the devolution settlement”.
He wrote: “I am aware that stakeholders in Scotland are keen to see that the UNCRC Bill is given royal assent as soon as possible.
“While the UK Government and Scottish Government have different views on the benefits of incorporating conventions into statute, as set out above we respect Scottish Parliament’s ability to legislate on this in devolved areas.
“However, doubt about the competence of specific provisions in the Bill serves no one.
“I would have preferred not to have been in this situation. We do all we can to respect the devolution settlement and resolve disputes.
“It is important that all legislation clearly reflects the competence and roles of Scotland’s two parliaments and governments.
“This need for clarity, not just for us, but for the children the UNCRC Bill is intended to protect and the stakeholders who represent them, is why I think it is essential that both governments respect the devolution settlement and we work collaboratively to resolve issues.”
Deputy First Minister John Swinney said: “Once again, we are seeing the tale of two governments play out in front of us, with the one in Holyrood passing landmark legislation to incorporate children’s rights into decision-making and the Tories at Westminster threatening to rip the Bill up in a blatant power grab.
“The UNCRC bill passed with cross-party support last week and was widely celebrated - so it is quite extraordinary that Alister Jack is now threatening to trample all over devolution and block this landmark legislation that puts children’s rights at the heart of all our decision-making.
“Power grabs have been par for the course with this UK Tory government as they continue to undermine the devolution settlement - it's abundantly clear they have no respect for our Scottish Parliament."