But one of them warned that the patience of the courts might soon be exhausted if investigators did not speed up their inquiries into Capt Maychell, who has been charged under Section 1 of the Official Secrets Act.
Capt Maychell, 32, has effectively been held in solitary confinement since she was arrested on 22 November. She is a Territorial Army officer serving with the Intelligence Corps.
Her lawyers applied for a writ of habeas corpus to force her release and for a judicial review. They were rejected by Lord Justice Kennedy and Mr Justice Clarke last week. Yesterday the judges issued an edited version of their written judgment. Lord Justice Kennedy said: 'The effect of additional material placed before us is such as to satisfy me that we are dealing here with what is a very serious and, to some extent, complex investigation.'
The scale of the inquiry had to be balanced against the conditions in which Capt Maychell, from Morecambe, Lancashire, was being held. However, the judge said that Capt Maychell's detention for two-and-a-half months was not an excessive 'let alone oppressive' delay.
The Crown had disclosed that it could be another three months before inquiries were finished. The judge said that at future hearings courts would want evidence that investigations had proceeded as quickly as possible.
Mr Justice Clarke said: 'At present I would not hold that the detention is oppressive but the stage may well come in the not too distant future when it should be right to hold that the detention is oppressive and therefore unlawful.'
A Ministry of Defence spokesman said: 'We are not going to prolong matters any longer than we have to but there is a lot of fairly complex investigation to be done.'
However John Wadham, legal officer for Liberty, the civil rights group, said: 'We are extremely concerned about this case because a person is being remanded in custody in conditions of secrecy.'
The judgment revealed some further details about the case. On 21 November, Capt Maychell was invited to go to London for an interview and then placed under close arrest.
Her briefcase was seized and 52 bags of documents taken from her home by officers from the Army's Special Investigations Branch. She admitted two unauthorised visits to a foreign state and was charged with related offences.
Her solicitors said that the charges were trivial but her commanding officer disputed this and suggested that she would flee if she was released from custody.
On 18 January she was questioned by the SIB about a classified secret document which was in her briefcase when she was arrested. She was then charged with a third offence.
It was alleged that Capt Maychell knew the document was classified as secret and had obtained it for an improper purpose. But she said she believed it to be 'only exercise material'.Reuse content