Attorneys working with the more than 300 antinuclear demonstrators arrested Monday at the Pentagon sharply questioned a federal judge's decision yesterday to keep six of the demonstrators in jail because they refused to give him their names.

"My gut feeling is that's not constitutionally permissible," said attorney Sebastian Craber. He said lawyers for the Coalition for a Non-Nuclear World are researching the issue to see if District Court Judge Albert V. Bryan Jr. acted properly and may challenge him in court next week.

Yesterday, nine demonstrators were brought before Bryan for arraignment in Alexandria on misdemeanor charges of obstructing Pentagon entrances -- part of a mass "civil disobedience" action" by hundreds of protesters at the huge Defense Department headquarters building.

Three of the nine gave their names yesterday, pleaded no contest and were released by Bryan, who said the time they have spent in jail would count as their sentence.

The other six demonstrators refused to give their correct names, citing a range of philosophical and political reasons for non-cooperating with the judicial system. Bryan ordered them held in jail until they provided correct identification.

Graber said several other "non-cooperators" who refused to give their names were released by federal magistrates earlier this week.