The police officer who was poisoned in the Salisbury Novichok attack three years ago is suing Wiltshire Police.
Nick Bailey has lodged papers in the High Court because of the trauma he still experiences after being exposed to the poisonous substance in March 2018.
He spent 17 days in intensive care at Salisbury District Hospital after coming into contact with the nerve agent when he entered the house of former Russian spy Sergei Skripal.
He later announced his retirement from the force because of the difficulties he faced following the incident.
Patrick Maguire, partner at national law firm Horwich Cohen Coghlan, who is representing Mr Bailey, said: "It has been a challenging three years for everyone affected by the events of March 2018.
"Our client experienced a trauma which had a devastating effect on his family and forced him to leave the job he loved after more than 18 years of loyal service.
"We hope to come to a resolution very soon with Wiltshire Police so that Mr Bailey and his family can continue the process of healing and move forwards with their lives."
Mr Bailey left Wiltshire Police after 18 years in October last year after making three attempts to go back to work.
More on the Salisbury Novichok attack:
He described how he "couldn't deal with being in a police environment" after efforts to return in September 2018 and in January 2019.
Mr Skripal and his daughter Yulia survived the attack but the incident later claimed the life of Dawn Sturgess, 44, after she came into contact with a perfume bottle believed to have been used in the attack and then discarded.
Her partner, Charlie Rowley, was left seriously ill but recovered.
Two Russian nationals have been accused of travelling to the UK to try to murder Mr Skripal with Novichok, smearing the highly toxic substance on the door handle of his home in Salisbury.
Evidence gathered by intelligence agencies led the Government to conclude the men were officers from the Russian military intelligence service, the GRU.
The suspects - known by the aliases Alexander Petrov and Ruslan Boshirov - were caught on CCTV in Salisbury the day before the attack.
Moscow has repeatedly denied any involvement, with President Vladimir Putin claiming the two suspects were civilians, and the pair stating in an interview that they were tourists visiting Salisbury Cathedral.
Wiltshire Police declined to comment for legal reasons.