The European Court of Human Rights (ECHR) in Strasbourg has rejected an appeal from Scot Sandy Mitchell and three other men who are seeking damages from Saudi Arabia through the UK courts for alleged torture.
The ECHR's decision follows a House of Lords ruling in 2006 which said officials could not be sued due to state immunity.
However, Tamsin Allen has claimed Strasbourg is reluctant to rule against the UK Government because of Westminster's "hostility" to the European Court of Human Rights.
The four men who began the legal case - Mr Mitchell, fellow Scot Ronald Jones, Leslie Walker and William Sampson - were among six Britons who were imprisoned in Saudi Arabia in 2000 over a series of car bombings in Saudi Arabia.
The men always denied responsibility, and there were claims Islamic militants were behind the bombings. All of the men were eventually released and medical reports later backed their accounts of torture.
After an initial bid to sue the Saudi authorities through the UK courts ended in failure in 2004, the Court of Appeal ruled the suspected individual torturers could be sued.
However, in 2006, a committee of law lords, who have now been replaced as the highest court in the land by the Supreme Court, said that decision had been flawed, prompting the men to take their case to Strasbourg.
Ms Allen, of Bindmans legal firm, said it was scandalous the ECHR had taken more than seven years to reach its conclusion in the Saudi case, during which time one of the torture victims, William Sampson, had died.
She said: "There is a suggestion in some recent ECHR decisions that the ECHR will be reluctant to rule against the UK. My own view is that this is as a result of the Government's hostility to the EU and the Convention [on human rights] and its refusal to comply with the court's rulings. That is serious cause for concern."
"Although the issue of state immunity for foreign torturers is by no means clear in international law, the ECHR has missed a golden opportunity to clarify the law and to ensure there is redress for torture victims in the EU."
Mr Mitchell now plans to continue his fight by lodging an appeal with the Grand Chamber of the ECHR, which has the authority to make a final decision, within the next three months.
The 58-year-old, who is originally from Glasgow but now lives in West Yorkshire, said he intends to continue his battle for justice for the rest of his life.
He said: "The European Court has now come down on the side of the defendants who are the British Government - that is devastating. But there is one avenue left open to us and that is to appeal to the Grand Chamber of the European Court.
"We have come this far, it has taken us years and it's not about money any more, it's more about justice. Any British national can be tortured by a foreign power and there is no legal avenue of redress to them. If it takes me the rest of my life I will continue to pursue it to my dying day."
A spokesman for the Foreign and Commonwealth Office said: "The United Kingdom Government condemns the use of torture, and works to prevent it from occurring anywhere in the world.
"However, this case was not about the substance of the allegations but a fundamental legal point about state immunity which it was important to uphold.
"The government is pleased that the court has agreed with its arguments."