Immigration and race equality groups are to argue that immigration controls on visitors from other member states breach the Treaty of Rome - Article 8a provides for the free movement of 'goods, persons, services and capital' within the community from 1 January this year.
Fourteen members of the Standing Conference on Race Equality in Europe put the issue to the test with a return trip to Calais. They complied with no less than three separate passport checks at Dover at the start of their journey. But on their return, they refused to show any documentation, citing Article 8a to immigration officials.
Don Flynn, from the Joint Council for the Welfare of Immigrants, was served with a formal notice that 'as a person unknown' he was required to submit to further examination or be returned to France.
The group argued that it would take appropriate legal action. In the event, a serious confrontation was avoided when immigration officers accepted the word of the hovercraft operators that all passengers had carried passports. The party was allowed into Dover.
However, the group had not been given free passage when they entered Calais either. A French immigration official had chased a black woman and demanded that she hand over her passport.
In fact none of the 12 member states have so far dropped all internal checks - but nine have agreed to do so from 1 December, when extra policing and immigration controls have been established on the EC's external borders.
After that date travellers from France, Portugal, Italy, Germany, Spain, Greece, Belgium, the Netherlands and Luxemburg will be able to pass freely across ports and airports. But those from Britain, Ireland and Denmark will still be subject to the same immigration checks as other international travellers arriving in the free-travel areas.
Mr Flynn, who is to seek a judicial review of government immigration policy, said yesterday: 'We think the law is clear. From 1 January the European Community became an area without internal frontiers.'
But the Home Secretary is expected to launch a fierce defence. 'Our interpretation of article 8a is that it allows us to make checks for serious crime, drugs and illegal immigration,' a Home Office spokesman said.