BRITISH government threats to withdraw from the European Convention on Human Rights (ECHR) are "recklessness of the worst sort", the LibDem's former Northern Ireland spokesman has said.
Alistair Carmichael said the international rights safeguards were "integral" to the Good Friday Agreement and that to disregard them was to "muck around with" the 1998 peace accord.
The Orkney and Shetland MP, who styles himself a "federalist", also believes that Boris Johnson is undermining the union, saying the Tory leader poses a greater threat to the future of the United Kingdom than "the SNP, Sinn Féin and Plaid Cymru put together".
Mr Carmichael's comments come amid growing speculation that the British government may pull out of the ECHR after judges granted an injunction that effectively grounded a flight sending asylum seekers to Rwanda.
The judgment was made on the basis that it would've infringed the ECHR.
The LibDem MP told The Irish News that the convention was central not only to the Good Friday Agreement but to "the whole devolution settlement around the United Kingdom".
"Ironically, I think it was originally intended as a protection for people living in areas where there were devolved administrations, to protect them from excesses of the administration – and it was a protection given to them by Westminster," he said.
"Now it's working the other way around – people living in devolved areas, rely on the Human Rights Act to protect them from Boris Johnson and this government."
Mr Carmichael said the ECHR was "integral" to the Good Friday Agreement.
"It's hardwired into the Good Friday Agreement, so if you muck about with the Human Rights Act or the European Convention on Human Rights, then you muck around with the Good Friday Agreement," he said.
"And that, to my mind, is just recklessness of the worst sort."
He said the current Tory administration professes to care about the union, "but then, piece by piece, they keep doing things to undermine it".
The LibDem MP said the Northern Ireland Protocol "potentially" undermines the constitutional integrity of the United Kingdom and believes the UK should have stayed in the Customs Union.
"But for Boris Johnson and his colleagues, the English nationalism that drives Brexit has always been more important to them than anything else, including the continued operations of the United Kingdom," he said.
"Ian Paisley himself said recently that Johnson behaves more like an English nationalist, and I think he's right about that."
Mr Carmichael said he supports the "continuation of the United Kingdom" but believes the Tory leader undermines the unionist cause.
"I think Boris Johnson is the biggest threat to the continuation of the United Kingdom, much bigger than the SNP, Sinn Féin and Plaid Cymru put together," he said.
"If you have a union, which is asymmetric, where the vast majority of people live in England, you've got to recognise that there will be necessary compromises to maintain the integrity of a union like that – Johnson isn't prepared to make these compromises."
He argues that the end of Boris Johnson's premiership "within months rather than years" will remove one of the main arguments for breaking up the UK.
