During a two-hour grilling by a select committee of MPs, the Home Secretary sought to defuse the threat of a Labour revolt over the Bill when it is introduced in the Commons.
He said there could be changes to the draft Bill before it starts its passage through Parliament in the face of widespread criticism.
Mr Straw also signalled that he would change the Bill to lift a blanket ban on the release of information on the investigation of accidents. The Bill could be amended to allow the release of information on accident inquiries, with a "harm test" where it is judged it would prejudice the public interest.
He admitted he was irritated at being cast as the "Prince of Darkness". "In fact, I have had the spotlight on the inner crevices of the Home Office since I got there," he said."There is a strong case for Government to develop its policy in private. That applies to every institution I know of. Government becomes impossible if you don't have that."
More than 20 organisations, from the British Safety Council to the Townswomen's Guild, attacked the legislation on the eve of the Commons hearing. Mr Straw is accused of tearing the heart out of the White Paper by David Clark, before he was sacked from the Cabinet.
Mr Straw said the proposed "harm tests" were flawed. " We decided it was not possible to have a substantial harm test which covered wide areas that were not the same.
"We are clear about certain of the key building blocks in this Bill, but this is a draft Bill and I have never embarked on the legislative process without a Bill being capable of improvement."
Denying that the White Paper had been watered down by senior civil servants, Mr Straw said: "This is not game, set and match to Sir Humphrey. Ministers are responsible for this Bill. Let me make that clear. It is not something that crept on us in the night, which I have ticked just before I take my cocoa before I go to bed."Reuse content