They will be suing for wrongful imprisonment and torture.
The former engineer told how, whatever the outcome, he will fight for the rest of his life to clear his name.
He said: "I'm on tenterhooks. This means everything to me. I want to be able to clear my name.
"If the decision goes in our favour, it will mean we can take the Saudi government or the individuals who tortured us to court.
"The fight will go on even if the decision goes against us."
Mr Walker was one of six Britons arrested in Riyadh following a series of bomb attacks on Westerners in 2000, which the Saudi authorities said was part of a turf war between rival illegal alcohol runners. He was sentenced to 12 years.
The men have always denied any involvement and are campaigning for the Saudi Arabian government to apologise, quash the bombing conviction and award damages.