Civil service union the FDA is challenging the government's handling of the controversial scheme to deport asylum seekers to Rwanda before a High Court judge today.
The union has expressed concerns that civil servants who comply with ministers' instructions to proceed with deportations of asylum seekers against European Court of Human Rights interim rulings will be breaking domestic law and the civil service code.
The FDA represents senior officials, including permanent secretaries and directors general. It says the Rwanda scheme, which has yet to result in any forced deportations, has been "fudged" by ministers in a way that is "cowardly" and "reckless" and which damages the integrity of the civil service.
The Safety of Rwanda (Asylum and Immigration) Act, which underpins the scheme, passed into law at the end of April. It gives ministers the power under UK law to decide whether to comply with any interim measure issued by the ECHR in relation to deportations of asylum seekers to Rwanda.
Cabinet Office guidance now requires civil servants to disregard ECHR rulings blocking deportation flights to Rwanda if told to do so by a minister. But the FDA says guidance alone is not strong enough and that civil servants working on deportations are being placed in an "impossible" position.
In its submission to the High Court, the union says it does not expect civil servants will refuse to implement a ministerial instruction. But it reports that members have expressed fears that they might be acting unlawfully by aiding the breach of an interim ECHR measure, and that they could potentially be exposed to civil or other liabilities.
The union wants the High Court to clarify whether failing to comply with interim measures sought by the ECHR at the request of a UK government minister is consistent with the obligations to uphold the law that are enshrined in the civil service code.
It will argue that the government's position is neither lawful nor legally effective because the civil service code cannot be altered by official guidance or overridden by an instruction from a minister.
FDA general secretary Dave Penman said the union had been forced to seek a judicial review of the government's position because ministers had failed to act decisively enough.
"We did not take this legal challenge lightly, nor did we welcome it," he said. "We’ve also been clear that this legal challenge is not to the policy itself – that is a matter for parliament.
"The government could have amended the civil service code to make clear that the obligation to comply with international law does not apply in these circumstances. But instead, it chose to fudge the matter and issue guidance which it knows cannot override the civil service code, any more than the instruction of a minister can.
"By leaving civil servants in an impossible position, we felt we had no choice but to ask the court to intervene."
The hearing, before judge Mr Justice Marin Chamberlain, is expected to conclude today. It is not known when the judgment will be given.
Earlier this week government lawyers said that no deportation flights under the Rwanda scheme would take place before 24 July – almost three weeks after the general election takes place.
The Labour Party has been clear that it will scrap the Rwanda scheme if it holds power following the election.