A judge has given permission for blood samples to be taken from Sergei and Yulia Skripal so that tests can be carried out by chemical weapons experts, following the pair's poisoning with a nerve agent.
Mr Justice Williams made the ruling following a hearing in the Court of Protection, since neither Mr Skripal, 66, or his 33-year-old daughter, are able to give their consent.
He also ruled that the pair's medical notes could be passed on to the Organisation for the Prohibition of Chemical Weapons (OPCW), as such moves were in their best interests.
OPCW experts were invited to the UK by the Government to assist with the investigation.
The pair remain unconscious and in critical but stable conditions following the March 4 attack in Salisbury.
The ruling came as Detective Sergeant Nick Bailey, the police officer who was poisoned by the Novichok nerve agent while working on the investigation into the targeted attack was discharged from hospital.
However, he said his "life will never be the same again" following his exposure to the poison more than two weeks ago.