The High Court has agreed to hear a challenge which calls into question a decision by the Director of Public Prosecutions (DPP) not to bring manslaughter charges against a firm after an employee was decapitated.

The action has been launched by the family of a student, 24-year-old Simon Jones, who was killed as he worked for Dutch-owned Euromin at Shoreham docks in West Sussex on 24 April 1998. He died two hours after starting his job as an untrained casual worker when his head was cut off by a crane while working on a dock side.

Now Deputy Judge Nigel Pleming QC has held that Jones' family has a "clearly arguable case" in its claims that the DPP and the Crown Prosecution Service (CPS) failed to consider the matter properly before deciding not to prosecute Euromin and its UK general manager.

The judge, who heard allegations that Euromin "sacrificed safety for profit", gave the go-ahead for Mr Jones' brother, Timothy, to mount the challenge.

Patrick O'Connor QC, acting for the family, claimed that the DPP and the CPS had been guilty of "irrationality and acted unreasonably" in deciding that there was insufficient evidence and "no reasonable prospect" of obtaining a conviction for manslaughter before a jury.

While he ruled out the possibility of a verdict of "unlawful manslaughter" being open to a trial jury, Deputy Judge Pleming said he was satisfied the family had an arguable case over the consideration given to the matter by the DPP and the CPS.

He said that in those circumstances, he had decided, though with some hesitation, that the case should be further investigated to see whether the DPP should in fact have allowed a prosecution to go ahead on the basis of the employers facing a charge of "manslaughter through gross negligence".

But, in doing so, he warned Jones' family that even though he considered that they had an arguable case, they faced "an uphill struggle" in convincing a full court hearing that the DPP had been wrong in blocking such a prosecution.