Sir Scott Baker told MPs he did not talk with British people fighting US extradition requests before publishing his official report.
The retired judge found earlier this year that the current extradition treaty with the US is fair, despite claims that it is biased against the British.
Sir Scott revealed he had spent a week with Washington legal officials but did not meet the family of Gary McKinnon, 45, a computer hacker with Asperger’s Syndrome, who has fought against extradition to America.
He was accused in 2002 of hacking into American military and Nasa computers, causing $700,000 (£445,000) of damage.
He admits breaching the systems but denies causing damage.
David Cameron was critical of the treaty while in opposition and Parliament this month voted for an “urgent reconsideration” of the law.
The UK allows extradition to the US on the grounds of “reasonable suspicion”. America will only hand over suspects to Britain if there is “probable cause”.
Sir Scott said that not a single Briton would have escaped extradition if the wording was the same in both countries.
He admitted that he had not found time to meet those campaigning on behalf of Mr McKinnon or other key cases such as Babar Ahmad, a terrorist suspect who has been detained without charge for seven years, or the Nat West Three, bankers indicted on fraud and since jailed and released.
“So although you managed to go to Washington for the week you weren’t able to call in people like David Bermingham of the Nat West Three, the McKinnon team or Babar Ahmad’s team,” said Keith Vaz, chairman of the home affairs committee.
Sir Scott said he had requested and accepted written evidence from all those with an interest in the extradition treaty.
“We had a great deal of material from everyone including them,” Sir Scott said.
“The suggestion that we don’t
understand the plight of persons sought to be extradited is, I’m afraid, not accepted.”
He also said that it was sometimes quicker and easier for suspects to be extradited from the US to the UK, rather than the other way around. Mr Vaz and several other MPs challenged the idea that the wording was the same for each country.
“One is about suspicion, the other is about belief,” Mr Vaz said. “In normal ordinary language if you suspect something it’s quite different from believing something surely?”
Sir Scott said “you couldn’t put a sheet of tissue paper” between the tests in each country.
“Nobody has drawn our attention to any single case at any stage where it would have made any difference whether you applied the American test or the United Kingdom test,” he said.
Dominic Grieve, the Attorney General, has said the review carried out by Sir Scott offered “guidelines only”.
