Bradley Manning who has now been held in solitary confinement for some 7 months in an American military prison. Manning is the person accused by the U.S. in connection with the supply to Wikileaks of American classified information. It is reported in the media that the U.S. Attorney-General Eric Holder is considering what type of plea bargain might be offered to Manning in exchange for information incriminating Julian Assange in the dissemination of the information supplied to Wikileaks - See The Independent 18th December 2010. (Such an approach appears to assume that there is some link between Manning and Assange whereas all they may have in common may be the Wikileaks computer system). Manning is reportedly in a bad state of health having been held in solitary and not permitted exercise. Needless to say, given his present situation, he is likely to find some form of plea bargain highly attractive since he would receive a very significantly lower sentence. This looks like a nasty strategy designed to "break" Manning in order to "get" Assange.
It is instructive to look at
the House of Lords judgment in McKinnon v U.S. Government  UKHL 59. Gary McKinnon is wanted by the U.S. in connection with computer offences. Details of the alleged criminality are set out in paras. 11 to 16 of Lord Brown of Eaton-under-Heywood's judgment. Lord Brown then set out details (paras. 18-20) of plea bargaining negotiations which took place between November 2002 and April 2003. What is striking is the considerable reduction in sentence which was then on offer if McKinnon were to admit two offences. An admission would have resulted in a sentence of 3-4 years with only 6 months served in the USA and the remainder in the UK. For non cooperation, a sentence of 8-10 years (maybe more) with no repatriation to the UK. Lord Brown pointed out (para 34) that actual practice in the English system recognises credit for guilty pleas and he noted that it is common for prosecutors to agree to accept guilty pleas to lesser charges in exchange for more serious charges being discontinued.
Reference should be made to Guidelines issued by the Attorney-General. These include (a) Plea discussions in cases of serious and complex fraud - 18th March 2009 and (b) Acceptance of Pleas (revised 2009). Modern law on getting a sentence indication in the event of a guilty plea is based on R v Goodyear  EWCA Crim 888 where the Court of Appeal sought to ensure common process and continuing safeguards against the creation or appearance of judicial pressure on the defendant. Seeking a "Goodyear indication" is a common phrase in the Crown Court. An interesting article on this appeared in the Criminal Bar Quarterly October 2010 - see the article by John Edwards and Richard Gibbs "Goodyear - losing its grip?"
Further legislation in this area is the Serious Organised Crime and Police Act 2005 sections 71-75 (as amended from 6th April 2010 by the Coroners and Justice Act 2009 s113) which amongst other things enables prosecutors to offer immunity from prosecution in exchange for information received (s.71 "immunity notices") and courts may take into account assistance offered by an offender when sentencing (s.73). Those sections entered into force on 1st April 2006 and are said to have formalised and developed common law principles relating to what was known previously as "Queen's Evidence." The leading case on the sections is R v Blackburn  EWCA Crim 2290. For a recent case relating to s.73 see R v Dougall  EWCA Crim 1048.
There are significant differences between the US system (or more exactly systems) and English criminal practice. Nevertheless, the situation is not without concerns and it is essential to ensure that persons are dealt with fairly in any process resulting eventually in a guilty plea. One wonders whether that would apply to Bradley Manning.
"The under-appreciated heroes of 2010" - including Bradley Manning - The Independent 24th December.
Addendum 24th January 2011: "Lawyers condemn 'abuse' of suspected WikiLeaker Bradley Manning" - The Guardian.
Addendum 3rd March 2011: It is reported that a charge of "assisting the enemy" might be preferred against Bradley Manning and that he might face the death penalty. The Guardian 3rd March 2011.
Did Bradley Manning assist the enemy ... did the New York Times? Opinio Juris.
Addendum 4th March 2011: "Terror suspects could walk in push for prosecution "deals" - Tom Whitehead in The Telegraph 3rd March 2011.
Addendum 14th March 2011: "The shameful abuse of Bradley Manning"- The Guardian refers to the shameful treatment of Bradley Manning