A JUDGE has ordered the Government to explain the legal basis for detaining a group of 34 Vietnamese boat people in a landmark legal case which could lead to costly compensation claims for false imprisonment and the release of hundreds of others. The case, known to be closely monitored by the foreign ministries of Vietnam and China, began yesterday when Mr Justice Kaplan allowed that a prima facie case had been established for a hearing into the legality of detaining the 34 people, who include 11 families. Solicitors' firm Pam Baker and Company have launched the action in the hope it will set a precedent for seeking the release of others whom the firm claims are being held illegally. Human rights expert, barrister Philip Dykes, represented the boat people. The case, a habeas corpus action, is set down over at least three days from December 16. The Government has been ordered to make a written submission to the court three days before the hearing. Last month, the Government released 125 people to avoid legal action it said the Crown would certainly have lost. The 125 were released after their repatriation applications were rejected by Vietnam on the basis they were not Vietnamese citizens. After yesterday's brief court hearing, the lawyers learned one of the 11 families would be released on family reunion grounds. Chung Tu Quan, who is seven months pregnant, and her four-year-old son, Tran Dao Phong, are to be allowed to join her husband and father, one of the 125 people released. Of the other applicants, lawyers said four families had been classified as ex-China Vietnamese illegal immigrants, although three families had never lived in China. Two single men who were screened out and have been rejected for voluntary repatriation are among the applicants. Three families had foreigner status in Vietnam as Taiwanese nationals. Two families have expired Taiwanese passports. They have not applied for voluntary repatriation, but their lawyers say they would be rejected if they did apply, because Vietnam has a rigid policy of refusing the repatriation of people who are not Vietnamese nationals. Secretary for Security Alistair Asprey said yesterday no one was being held illegally and that legal officers would be looking at individual cases in preparation for the hearing. He said there was a marked difference in the situation of the 125 who had been released and those in the habeas corpus claim. 'The essential difference is in certainly many, most perhaps, of the 125 cases, we had actually had a rejection by the Vietnamese Government. That does not apply to anybody else in detention,' Mr Asprey said. If it loses the case, the Government faces the prospect of having to release dozens and possibly hundreds of others against the wishes of China and most of the Hong Kong community. Almost 24,000 boat people remain in Hong Kong detention centres and must be repatriated under an international agreement.