By Peter Wozniak
The flagship Conservative immigration policy is to be challenged at the High Court as unlawful, it has emerged.
The controversial cap on immigration from outside the EU will be the subject of a legal battle that the Home Office will be keen to avoid.
The allegation is that the Home Office, in instigating the cap in preparation for a final agreement to bring down non-EU immigration from "hundreds of thousands to tens of thousands", bypassed parliament in announcing the moves.
The immigration minister Damian Green remained bullish about the troubled policy's chances of success.
"We will rigorously defend this challenge and are confident of success. The government has been clear, we will introduce our permanent annual limit on economic migrants from outside the EU from April 2011", he said.
"While we decide how the annual limit should operate it is imperative that we have interim measures in place to avoid a rush of applications from migrants before the new rules take effect."
The cap is a subject of tension between the coalition partners, with business secretary Vince Cable openly against the policy, arguing that it will damage British competitiveness.
Some of the fiercest exchanges in the prime ministerial debates were between Nick Clegg and David Cameron on the issue, though the policy did survive the creation of the coalition agreement.
Over the summer the courts ruled against the home secretary on imposing the temporary cap as unlawful given her side-stepping of parliament.
The legal battle is potentially hugely embarrassing for home secretary Theresa May, though it may secretly delight many Lib Dems.