The Serious Fraud Office (SFO) acted "unlawfully" in dropping its investigations into alleged bribery and corruption involving BAE Systems and Saudi Arabian arms dealings, the High Court ruled today (10 April).

A judgement handed down this morning by Lord Justice Moses and Mr Justice Sullivan ruled in favour of claimants – Corner House Research and the Campaign Against Arms Trade – who argued commercial interests were behind the controversial decision to drop the probe into BAE's £43bn Al Yamamah arms contract with Saudi Arabia.

The investigation into corruption, which began in 2004, was dropped in December 2006 by then-Attorney General Lord Goldsmith over national security concerns. The decision was widely viewed as having come amid pressure from the UK Government concerned that the Saudi administration would stop co-operating with anti-terrorism efforts if the investigation was not stopped.

The claimants argued that the decision to drop the probe breached an international anti-bribery convention.

It is not clear what the SFO's next move will be following the decision, with speculation rising over whether the probe could be re-opened. In an official statement, the SFO said it is "carefully considering the implications of the judgment and the way forward".

Leigh Day & Co advised the claimants, with Blackstone Chambers' Dinah Rose QC and Matrix Chambers' Philippe Sands QC instructed as counsel.

Allen & Overy advised BAE Systems, with Matrix Chambers' Clare Montgomery QC instructed as counsel. The director of the SFO was advised by Treasury solicitors and 11KBW's Philip Sales QC.

The result will be seen as a victory for campaigners and a blow to the UK's credibility for combating white-collar crime.

Mishcon de Reya litigation partner and civil fraud specialist, Dan Morrison commented: "I don't think anybody in the legal community thought the outcome would be any different, bearing in mind the obvious reason for the inquiry not going ahead was political rather than legal."

He added: "Equally, it is naive to think that the way to resurrect these things is to challenge legally. Is the Government now going to re-open the investigation? I think it would be doubtful."

Peters and Peters civil fraud partner Steve McCann commented: "Whatever the specific criticism made of individuals and agencies, the findings are an exemplar of the judiciary's independence."