As it was, when no explosives were found and the Crown Prosecution Service was unable to collect sufficient evidence, the men were released without being charged but ordered to leave the country.
Mr Naseer avoided being sent to Pakistan after arguing that he would be mistreated there. He was eventually deported to the US in January 2013 after prosecutors announced they wanted to charge him with trying to blow up the New York subway and Manchester's Arndale shopping centre.
Mr Naseer has denied the charges and said that he wanted to represent himself in court. He said that the time he spent on Muslim internet sites like Qiran.com was part of his quest to find a bride.
Denying that he was a member of al-Qaeda, Mr Naseer referred to himself in the third person and said on Tuesday: "He has no extremist or jihadist views."
The trial of Mr Naseer, which is expected to take a number of weeks, is significant for many reasons, not least the efforts by the authorities in the US to bring him to trial.
The hearing will be the first to include evidence discovered in the Abbottabad compound of Osama bin Laden by US special forces who flew into Pakistan and killed the al-Qaeda leader in the spring of 2011.
A US judge ruled last month that six agents who conducted surveillance on Mr Naseer in Manchester could protect their identities after hearing they still worked on sensitive undercover cases. US District Judge Raymond Dearie also said the agents could wear light make-up and be identified using numbers rather than their real names.
Prosecutors introduced testimony from the first of two witnesses, Najibullah Zazi and Zarein Ahmedzay, who both pleaded guilty to taking part in a thwarted plot to detonate home-made explosives in the New York subway.
Prosecutors claim that email account evidence shows all three men were under the direction of the same al-Qaeda handler.
The Associated Press said Mr Naseer objected several times when Mr Zazi, a former New York resident, gave his evidence. One of his interventions was to object to the introduction of a photograph of bin Laden.
"I agree with you that this case is not about 9/11," Judge Dearie told Mr Naseer during a break. The judge decided, however, that Mr Zazi should be able to refer to bin Laden in describing how he became radicalised.
In a lengthy written statement submitted during the deportation proceedings, Mr Naseer claimed to come from a moderate Muslim family that stressed education.
He said he went to Britain to get a degree in computer science, not to attack the West. "Committing terrorist acts is not justified and I do not consider this to be jihad," he added. "I believe in spiritual jihad."The trial continues.