PER CURIAM
Appellants, subpoenaed by the prosecution to testify in a criminal trial currently in progress in the District Court and granted use immunity for that purpose, refused to testify and were held by the District Court to be in civil contempt. They appeal that judgment and challenge its validity on a number of grounds. For the reasons hereinafter appearing, we find none of their contentions to be availing, and we affirm.
I
On August 15, 1978, an indictment was returned charging appellants (Hubbard, Heldt, Weigand, and Willardson) and seven other persons, including the defendants in the current criminal case (Kember and Budlong), with a number of federal and D.C.Code offenses. The latter consisted of ten counts of burglary, which were charged against both appellants and Kember and Budlong. On the same day warrants were issued for the arrest of Kember and Budlong, who were in England, and the United States promptly requested the United Kingdom to extradite them. On October 26, 1979, appellants were convicted in a non-jury trial on stipulated evidence of one count of conspiring to obstruct justice (a federal offense). The presiding judge also enforced an asserted agreement under which the appellants, convicted of the one count, were to have all the other counts against them in the indictment dismissed if the conviction was not reversed on appeal; if, contrarily, the conviction was reversed, the prosecution could proceed on any of the remaining offenses charged in the indictment. On December 6, 1979, appellants were sentenced to prison terms and fined. Since December 21, 1979, they have been at liberty on bail pending appeal. On March 13, 1980, the extradition proceedings against Kember and Budlong were at long last completed after traversing the entire English judicial hierarchy from Bow Street Magistrate to the House of Lords (with a further futile application to the Home Secretary and the European Commission of Human Rights), and they were returned to the United States and arraigned before a federal magistrate in Washington, D. C. The Government represented to the magistrate that, under the terms of the British extradition order, Kember and Budlong could be prosecuted only on the D.C.Code offenses joined in the indictment, i. e., the burglary counts. Their trial on these counts began in the District Court on October 27, 1980. In anticipation of that trial, the Government subpoenaed the appellants to appear and to testify. A joint motion by appellants to quash the subpoenas was denied by the District Court on October 21, 1980 on the eve of trial. At the trial itself, appellants were called as the prosecution's first four witnesses. After stating their names, they declined to answer all other questions put to them, claiming their privilege against self-incrimination under the Fifth Amendment, as well as rights under the First, Fourth, and Sixth Amendments; they also urged that the court lacked jurisdiction to enforce the subpoenas. They were then granted immunity against use of their testimony under 18 U.S.C. ss 6001 et seq., and were directed by the court to respond to the questions, but they refused to do so. After a voir dire hearing outside the presence of the jury, in which appellants renewed their earlier objections, the court made its contempt adjudication, but released appellants on their personal recognizance pending appellate review of the court's action.