The U.S. government on Wednesday asked the British High Court to overturn District Judge Vanessa Baraitser’s decision to prevent WikiLeaks founder Julian Assange from being extradited to the United States to face espionage charges.

While Judge Baraitser refused extradition on health grounds, lawyers for the U.S. authorities, having been granted permission to appeal, challenged the psychiatric evidence in Assange’s case at an earlier hearing, arguing that he had not reached the threshold of being “so ill” that he might harm himself.

Assange, who is being held at the maximum-security Belmarsh Prison in London, did not attend the earlier hearing, although he was due to appear via video.

U.S. prosecutors have charged Assange with 17 espionage charges and another charge of computer misuse in connection with WikiLeaks’ release of thousands of leaked military and diplomatic documents, all of which carry a minimum sentence of 175 years in prison.