Plans to make it easier to convict British terror suspects have been condemned by a group of leading barristers.
Blunkett's has come in for criticism on the proposals
The group have been approved to work as special advocates in immigration cases but oppose plans to roll out the scheme to include UK terror suspects.
David Blunkett is considering non-jury trials, which would happen in secret.
But the Home Office says no decisions have yet been taken and such proposals would need new legislation.
Limits on disclosure
A spokesman said a full options paper would soon be published and Mr Blunkett wanted to consult with the relevant parties.
Five of the barristers due to play a central role in the plans have described the idea of secret non-jury trials as "untenable".
In an as yet unpublished letter sent to the Times, but seen by the BBC, they say the special advocate system does not contain the "fundamentals of a fair trial".
And, in a clear indication they would refuse to take part, they say "an unfair trial determining guilt is not something we could be associated with".
The home secretary also suggests there could be a lower burden of proof in order to convict.
Under the proposals, defendants would be represented by special advocates cleared to hear sensitive material.
They would not be allowed to disclose such evidence - even to those they represent.
Shadow home secretary David Davis has already said the plans risked "throwing away the very freedoms we are fighting for" - and called the proposals "yet another of David Blunkett's kite-flying operations".
Civil rights groups have also condemned the proposals as shameful and an "affront to the rule of law".
And a lawyer for Feroz Abbasi, one of the Britons held at Guantanamo Bay in Cuba, said Mr Blunkett's proposals showed he was not fit to be home secretary.
The Anti-terrorism, Crime and Security Act 2001 allows foreigners who are suspected international terrorists to be detained indefinitely without charge or trial in the event their lives would be in danger if they were deported.
Britain is holding 14 foreign terror suspects under this law, based on evidence which is tested in secret.
Mr Blunkett wants to extend this so prosecutors can take action against suspected British extremists even though the evidence may not be strong enough to win a conviction under existing laws.
Hence the possible need to lower the standard of proof in such cases from "beyond reasonable doubt" to what is acceptable in civil cases, "the balance of probabilities".
Evidence in the new trials would be kept secret from the defendants to protect MI5, MI6 and GCHQ intelligence sources, Mr Blunkett said.
Speaking on a tour of the Indian sub-continent, Mr Blunkett said: "We have to have prevention under a new category
which is to intervene before the act is committed, rather than do so by due
process after the act is committed when it's too late."