Extremists Salahuddin Amin and Rangzieb Ahmed, both British citizens, claim their trials were unfair because UK spies knew some of the information used against them was obtained during their torture by Pakistani security services.
Their argument has previously been rejected by the UK courts.
Now the pair have been given a green light to put their case to the European Court of Human Rights in a last-ditch bid to be freed.
If the case is not thrown out it will be the first time British terrorist convictions have been challenged in Strasbourg.
It has provoked outrage because the European Court would normally have declared the case inadmissible – as it does 400,000 each year – because the claim hinges on a point of fact, rather than one of law or procedure.
Lawyers have criticised the rising influence of unelected judges over British sovereignty. Read More