It was the first major test of a new terrorism law that lets the government hold suspects for as long as 28 days without charge so investigators can solidify their cases.
The hearing, which addressed the cases of 23 suspects arrested in Britain's initial sweep last week, was held behind closed doors and attended only by the suspects' lawyers, investigators and government officials.
However, Scotland Yard said Wednesday night that a person arrested earlier this week as part of its investigation was released. In a brief statement, police said the suspect was released without charge. Scotland Yard said the suspect had been arrested on Monday.
Earlier Wednesday, Scotland Yard said that 21 of the suspects could be detained for questioning through Aug. 23, while another two could be detained until Aug. 21. No reason was given for the difference in the length of time.
The final suspect, who was arrested Tuesday, was not involved in the hearing, Scotland Yard said, adding that he remained police custody.
As CBS Radio News correspondent Charlie D'Agata reports, new anti-terror laws give the British government up to four weeks to hold suspects without charges — but lawyers must periodically appear before a judge to make the case for continued confinement.
Experts say the primary reason police could use nearly a month to complete a probe is because of the complexity of investigations into the alleged plot to smuggle liquid explosives hidden in hand luggage aboard flights.
"You've got laptops, you have to bring in translators to translate all the documents in there, and sometimes it's inopportune to release all your suspects — particularly terrorism suspects — while all that is being downloaded and translated," said Cliff Knuckey, a retired police detective who has worked on terrorism investigations.
"Terrorism investigations are different, simply because you're dealing with people who will do their best not to compromise their plans and who will do anything not to be compromised."
What the police do not want to do is bring serious charges and see them collapse, CBS News correspondent Sheila MacVicar reports. There is concern that police were pushed to disrupt the plot before they had enough firm evidence.
When police officials appeared in February before a House of Commons committee looking at Britain's terror legislation, they told lawmakers much the same thing. Deputy Assistant Commissioner Peter Clarke, who commands the anti-terrorist police branch, said officers had found terrorist training videos spliced in the middle of normal Hollywood films, meaning hours spent scrutinizing videotapes.
Previously, police were able to detain people suspected of terrorism offenses for 14 days only. But the new legislation, which became law earlier this year, also created new offenses, including preparing a terrorist act, giving or receiving terrorist training, and selling or spreading terrorist publications.
Prime Minister Tony Blair failed to receive parliamentary approval for his own plan to interrogate terrorist suspects for up to 90 days.
The British probe of a plot to destroy U.S.-bound jetliners with chemical explosions is the highest-profile case to be conducted under the new legislation.
Home Secretary John Reid, Britain's chief law-and-order official, acknowledged that some of the suspects likely would not be charged with major criminal offenses, but said there was mounting evidence of a "substantial nature" to back the allegations.